Random Access Method and Device

ABSTRACT

A random access method including receiving, by a user equipment, a radio resource control (RRC) connection reconfiguration message from a first network device, where the RRC connection reconfiguration message is included in a first message sent by a second network device to the first network device, and where the RRC connection reconfiguration message indicates a primary serving cell of the second network device for the user equipment, and further indicates an active bandwidth part (BWP) in the primary serving cell, and the method further including initiating, by the user equipment, a random access procedure on the active BWP.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/CN2018/112391, filed on Oct. 29, 2018, which claims priority toChinese Patent Application No. 201711132799.X, filed on Nov. 15, 2017.Both of the aforementioned applications are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

This application relates to communications technologies, and inparticular, to a random access method and a device.

BACKGROUND

With continuous development of communications technologies, research andstandardization on a 5th Generation (5G) mobile communicationstechnology are underway. User equipment needs to access a networkdevice, and therefore a random access procedure is still required in the5G technology.

In the prior art, a plurality of uplink bandwidth parts (BWP) areconfigured for user equipment. However, only one uplink BWP is in anactive state, and the user equipment can send a message and the like toa network device by using the uplink BWP in the active state. In arandom access procedure, the network device sends a message 0 to theuser equipment. The message 0 is used to trigger the user equipment toperform random access. The user equipment sends a message 1 to thenetwork device on the uplink BWP in the active state. The message 1includes a random access preamble. The network device sends a message 2to the user equipment. The message 2 is a random access response (RAR)message, the RAR message includes an uplink scheduling resource (ULgrant), and the UL grant is a UL grant corresponding to the uplink BWPused by the user equipment to send the message 1 to the network device.Then the user equipment sends uplink data to the network device by usingthe UL grant.

However, in the prior art, different BWPs may have differentconfiguration information, and the configuration information includes atransmission time length and/or a parameter set of a subcarrier spacingand a cyclic prefix length. In the random access procedure,configuration information of the uplink BWP used by the user equipmentto send the message 1 to the network device may not match configurationinformation required when the user equipment sends the uplink data tothe network device. Therefore, the user equipment cannot send the uplinkdata by using the UL grant that is in the RAR message and thatcorresponds to the uplink BWP, wasting the UL grant that is in the RARmessage and that corresponds to the uplink BWP.

SUMMARY OF THE INVENTION

This application provides a random access method and a device, toresolve a problem that a UL grant that is in an RAR message and thatcorresponds to an uplink BWP is wasted.

According to a first aspect, this application provides a random accessmethod, where the method includes receiving, by user equipment, controlsignaling sent by a network device, where the control signaling is usedto trigger the user equipment to perform a random access procedure, andthe control signaling includes or indicates a BWP identifier, andinitiating, by the user equipment, a random access procedure based onthe control signaling.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, the initiating, by the user equipment, a randomaccess procedure based on the control signaling includes initiating, bythe user equipment, the random access procedure on a BWP correspondingto the BWP identifier.

In a possible design, before the initiating, by the user equipment, arandom access procedure based on the control signaling, the methodfurther includes activating, by the user equipment, the BWP.

In a possible design, the BWP is an uplink BWP.

In a possible design, the initiating, by the user equipment, the randomaccess procedure on a BWP corresponding to the BWP identifier includessending, by the user equipment, a random access preamble to the networkdevice on the uplink BWP, receiving, by the user equipment, a firstrandom access response (RAR) message sent by the network device, wherethe first RAR message includes a first uplink grant (UL grant), andperforming, by the user equipment, uplink transmission on the uplinkBWP, where a physical resource used for the uplink transmission is aphysical resource indicated by the first UL grant.

In a possible design, the BWP is a BWP pair including an uplink BWP anda downlink BWP.

In a possible design, the initiating, by the user equipment, the randomaccess procedure on a BWP corresponding to the BWP identifier includessending, by the user equipment, a random access preamble to the networkdevice on the uplink BWP of the BWP, receiving, by the user equipment, asecond RAR message sent by the network device, where the second RARmessage includes a second UL grant, and performing, by the userequipment, transmission on the uplink BWP of the BWP, where a physicalresource used for the transmission is a physical resource indicated bythe second UL grant.

In a possible design, the control signaling received by the userequipment in any serving cell includes the BWP identifier, or thecontrol signaling received by the user equipment in any serving cellincludes the BWP identifier, where at least two uplink BWPs areconfigured for the user equipment in at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs, or the control signaling received by the user equipmentin a secondary serving cell includes the BWP identifier, or the controlsignaling received by the user equipment in the at least one secondaryserving cell includes the BWP identifier, where at least two uplink BWPsare configured for the user equipment in the at least one secondaryserving cell, and a random access channel is configured for each of theat least two uplink BWPs.

According to a second aspect, this application provides a random accessmethod, where the method includes sending, by a network device, controlsignaling to user equipment, where the control signaling is used totrigger the user equipment to perform a random access procedure, and thecontrol signaling includes or indicates a bandwidth part (BWP)identifier.

In a possible design, the control signaling is a physical downlinkcontrol channel order (PDCCH) order.

In a possible design, a BWP corresponding to the BWP identifier is anuplink BWP.

In a possible design, a BWP corresponding to the BWP identifier is a BWPpair including an uplink BWP and a downlink BWP.

According to a third aspect, this application provides a random accessmethod, where the method includes receiving, by user equipment, a randomaccess response (RAR) message sent by a network device, where the RARmessage includes or indicates a bandwidth part (BWP) identifier, andperforming, by the user equipment, uplink transmission on a first BWPcorresponding to the BWP identifier.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, before the performing, by the user equipment,uplink transmission on a first BWP corresponding to the BWP identifier,the method further includes activating, by the user equipment, the firstBWP.

In a possible design, before the receiving, by user equipment, an RARmessage sent by a network device, the method further includes receiving,by the user equipment, control signaling sent by the network device,where the control signaling is used to trigger the user equipment toperform a random access procedure, and sending, by the user equipment, arandom access preamble to the network device on a second BWP.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, before the sending, by the user equipment, arandom access preamble to the network device on a second BWP, the methodfurther includes activating, by the user equipment, the second BWP.

In a possible design, the control signaling includes an identifier ofthe second BWP.

In a possible design, the control signaling received by the userequipment in any serving cell includes the identifier of the second BWP,or the control signaling received by the user equipment in any servingcell includes the identifier of the second BWP, where at least twouplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in the at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In a possible design, the second BWP is a BWP in a first serving cell ofthe user equipment, and the first serving cell is a serving cell usedwhen the user equipment receives the control signaling, or the firstserving cell is a serving cell scheduled by using a second serving cellused when the user equipment receives the control signaling.

In a possible design, the first BWP is an initial active BWP of the userequipment in the first serving cell, or the first BWP is a first activeBWP of the user equipment in the first serving cell, or the first BWP isa default BWP of the user equipment in the first serving cell, or thefirst BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In a possible design, the first BWP and the second BWP are uplink BWPs,and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs.

In a possible design, the receiving, by user equipment, an RAR messagesent by a network device includes receiving, by the user equipment on athird BWP, the RAR message sent by the network device, where the thirdBWP is a downlink BWP, where the third BWP is an active BWP in thesecond serving cell when the user equipment receives the controlsignaling in the first serving cell, or the third BWP is a BWP used whenthe user equipment receives the control signaling in the first servingcell.

In a possible design, the first BWP and the second BWP each are a BWPpair including an uplink BWP and a downlink BWP, and the first BWP andthe second BWP may be a same BWP, or may be different BWPs.

In a possible design, the receiving, by user equipment, an RAR messagesent by a network device includes receiving, by the user equipment onthe uplink BWP of the second BWP, the RAR message sent by the networkdevice.

In a possible design, the receiving, by user equipment, an RAR messagesent by a network device includes receiving, by the user equipment on afourth BWP, the RAR message sent by the network device, where the fourthBWP is a BWP pair including an uplink BWP and a downlink BWP, where thefourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In a possible design, if the fourth BWP is a BWP used when the userequipment receives the control signaling in the first serving cell,after the sending, by the user equipment, a random access preamble tothe network device on a second BWP, the method further includesactivating, by the user equipment, the fourth BWP, and deactivating thesecond BWP.

According to a fourth aspect, this application provides a random accessmethod, where the method includes sending, by a network device, a randomaccess response RAR message to user equipment, where the RAR messageincludes or indicates a BWP identifier, and the BWP identifiercorresponds to a first BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, before the sending, by a network device, an RARmessage to user equipment, the method further includes sending, by thenetwork device, control signaling to the user equipment, where thecontrol signaling is used to trigger the user equipment to perform arandom access procedure.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, the control signaling includes an identifier of asecond BWP.

In a possible design, the second BWP is a BWP in a first serving cell ofthe user equipment, and the first serving cell is a serving cell usedwhen the user equipment receives the control signaling, or the firstserving cell is a serving cell scheduled by using a second serving cellused when the user equipment receives the control signaling.

In a possible design, the first BWP is an initial active BWP of the userequipment in the first serving cell, or the first BWP is a first activeBWP of the user equipment in the first serving cell, or the first BWP isa default BWP of the user equipment in the first serving cell, or thefirst BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access. In a possible design, the first BWP and the second BWPare uplink BWPs, and the first BWP and the second BWP may be a same BWP,or may be different BWPs.

In a possible design, the sending, by a network device, an RAR messageto user equipment includes sending, by the network device, the RARmessage to the user equipment on a third BWP, where the third BWP is adownlink BWP, where the third BWP is an active BWP in the second servingcell when the user equipment receives the control signaling in the firstserving cell, or the third BWP is a BWP used when the user equipmentreceives the control signaling in the first serving cell.

In a possible design, the first BWP and the second BWP each are a BWPpair including an uplink BWP and a downlink BWP, and the first BWP andthe second BWP may be a same BWP, or may be different BWPs.

In a possible design, the sending, by a network device, an RAR messageto user equipment includes sending, by the network device, the RARmessage to the user equipment on the uplink BWP of the second BWP.

In a possible design, the sending, by a network device, an RAR messageto user equipment includes sending, by the network device, the RARmessage to the user equipment on a fourth BWP, where the fourth BWP is aBWP pair including an uplink BWP and a downlink BWP, where the fourthBWP is an active BWP in the second serving cell when the user equipmentreceives the control signaling in the first serving cell, or the fourthBWP is a BWP used when the user equipment receives the control signalingin the first serving cell.

According to a fifth aspect, this application provides a random accessmethod, where the method includes receiving, by user equipment, a radioresource control RRC connection reconfiguration message sent by a firstnetwork device, where the RRC connection reconfiguration message isincluded in a first message sent by a second network device to the firstnetwork device, and the RRC connection reconfiguration message is usedto indicate the primary serving cell under the second network device forthe user equipment, and indicate an active BWP in the primary servingcell, and initiating, by the user equipment, a random access procedureon the active BWP.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a first BWP identifier, and a BWPcorresponding to the first BWP identifier is the active BWP.

In a possible design, the active BWP includes an uplink BWP and adownlink BWP, and the initiating, by the user equipment, a random accessprocedure on the active BWP includes sending, by the user equipment, arandom access preamble to the second network device on the uplink BWP inthe active BWP, receiving, by the user equipment on the downlink BWP inthe active BWP, a random access response RAR message sent by the secondnetwork device, where the RAR message includes an uplink grant UL grant,and performing, by the user equipment, uplink transmission on the uplinkBWP in the active BWP, where a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, the active BWP is a BWP pair including an uplinkBWP and a downlink BWP, and the initiating, by the user equipment, arandom access procedure on the active BWP includes ending, by the userequipment, a random access preamble to the second network device on theuplink BWP of the BWP pair, receiving, by the user equipment on thedownlink BWP of the BWP pair, an RAR message sent by the second networkdevice, where the RAR message includes a UL grant, and performing, bythe user equipment, uplink transmission on the uplink BWP of the BWPpair, where a physical resource used for the uplink transmission is aphysical resource indicated by the UL grant.

In a possible design, the first message is a response message sent bythe second network device after the second network device receives asecond message sent by the first network device, and the second messageincludes at least one of the following information: information about anuplink BWP or a BWP pair activated by the user equipment, informationabout all uplink BWPs or BWP pairs configured for the user equipment,and information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, or the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a sixth aspect, this application provides a random accessmethod, where the method includes receiving, by a first network device,a first message sent by a second network device, where the first messageincludes a radio resource control RRC connection reconfigurationmessage, and sending, by the first network device, the RRC connectionreconfiguration message to user equipment, where the RRC connectionreconfiguration message is used to indicate the primary serving cellunder the second network device for the user equipment, and indicate anactive BWP in the primary serving cell.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a first BWP identifier, and a BWPcorresponding to the first BWP identifier is the active BWP.

In a possible design, the active BWP includes an uplink BWP and adownlink BWP.

In a possible design, the active BWP is a BWP pair including an uplinkBWP and a downlink BWP.

In a possible design, before the receiving, by a first network device, afirst message sent by a second network device, the method furtherincludes sending, by the first network device, a second message to thesecond network device, where the second message includes at least one ofthe following information: information about an uplink BWP or a BWP pairactivated by the user equipment, information about all uplink BWPs orBWP pairs configured for the user equipment, and information about alogical channel of the user equipment, where the logical channel is alogical channel with a highest priority in all logical channels of theuser equipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a seventh aspect, this application provides a random accessmethod, where the method includes receiving, by user equipment, a radioresource control RRC connection reconfiguration message sent by a firstnetwork device, where the RRC connection reconfiguration message isincluded in a first message sent by a second network device to the firstnetwork device, and the RRC connection reconfiguration message is usedto indicate the primary serving cell under the second network device forthe user equipment, and indicate an active BWP in the primary servingcell, sending, by the user equipment, a random access preamble to thesecond network device on the active BWP, receiving, by the userequipment on the active BWP, a random access response RAR message sentby the second network device, where the RAR message includes orindicates a first BWP identifier, and performing, by the user equipment,uplink transmission on a first BWP corresponding to the first BWPidentifier.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a second BWP identifier, and a BWPcorresponding to the second BWP identifier is the active BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, before the performing, by the user equipment,uplink transmission on a first BWP corresponding to the first BWPidentifier, the method further includes activating, by the userequipment, the first BWP.

In a possible design, the first BWP is an uplink BWP, the active BWPincludes an uplink BWP and a downlink BWP, and the first BWP and theuplink BWP in the active BWP may be a same BWP, or may be differentBWPs, or the first BWP is a BWP pair including an uplink BWP and adownlink BWP, the active BWP is a BWP pair including an uplink BWP and adownlink BWP, and the first BWP and the active BWP may be a same BWP, ormay be different BWPs.

In a possible design, the first message is a response message sent bythe second network device after the second network device receives asecond message sent by the first network device, and the second messageincludes at least one of the following information: information about anuplink BWP or a BWP pair activated by the user equipment, informationabout all uplink BWPs or BWP pairs configured for the user equipment,and information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, or the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to an eighth aspect, this application provides a random accessmethod, where the method includes receiving, by a second network deviceon an active BWP, a random access preamble sent by user equipment, wherethe random access preamble is sent by the user equipment after the userequipment receives a radio resource control RRC connectionreconfiguration message sent by a first network device, and the RRCconnection reconfiguration message is used to indicate the primaryserving cell under the second network device for the user equipment, andindicate an active BWP in the primary serving cell, and sending, by thesecond network device, a random access response RAR message to the userequipment on the active BWP, where the RAR message includes or indicatesa first BWP identifier, and the first BWP identifier corresponds to afirst BWP.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a second BWP identifier, and a BWPcorresponding to the second BWP identifier is the active BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, the first BWP is an uplink BWP, the active BWPincludes an uplink BWP and a downlink BWP, and the first BWP and theuplink BWP in the active BWP may be a same BWP, or may be differentBWPs, or the first BWP is a BWP pair including an uplink BWP and adownlink BWP, the active BWP is a BWP pair including an uplink BWP and adownlink BWP, and the first BWP and the active BWP may be a same BWP, ormay be different BWPs.

In a possible design, before the receiving, by a second network deviceon an active BWP, a random access preamble sent by user equipment, themethod further includes receiving, by the second network device, asecond message sent by the first network device, where the secondmessage includes at least one of the following information: informationabout an uplink BWP or a BWP pair activated by the user equipment,information about all uplink BWPs or BWP pairs configured for the userequipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a ninth aspect, this application provides user equipment,where the user equipment includes a receiving module, configured toreceive control signaling sent by a network device, where the controlsignaling is used to trigger the user equipment to perform a randomaccess procedure, and the control signaling includes or indicates a BWPidentifier, and an access module, configured to initiate a random accessprocedure based on the control signaling.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, the access module is specifically configured toinitiate the random access procedure on a BWP corresponding to the BWPidentifier.

In a possible design, the user equipment further includes an activationmodule, configured to activate the BWP before the access moduleinitiates the random access procedure based on the control signaling.

In a possible design, the BWP is an uplink BWP.

In a possible design, the access module includes a first sendingsubmodule, configured to send a random access preamble to the networkdevice on the uplink BWP, a first receiving submodule, configured toreceive a first random access response RAR message sent by the networkdevice, where the first RAR message includes a first uplink grant ULgrant, and a first transmission submodule, configured to perform uplinktransmission on the uplink BWP, where a physical resource used for theuplink transmission is a physical resource indicated by the first ULgrant.

In a possible design, the BWP is a BWP pair including an uplink BWP anda downlink BWP.

In a possible design, the access module includes a second sendingsubmodule, configured to send a random access preamble to the networkdevice on the uplink BWP of the BWP, a second receiving submodule,configured to receive a second RAR message sent by the network device,where the second RAR message includes a second UL grant, and a secondtransmission submodule, configured to perform transmission on the uplinkBWP of the BWP, where a physical resource used for the transmission is aphysical resource indicated by the second UL grant.

In a possible design, the control signaling received by the userequipment in any serving cell includes the BWP identifier, or thecontrol signaling received by the user equipment in any serving cellincludes the BWP identifier, where at least two uplink BWPs areconfigured for the user equipment in at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs, or the control signaling received by the user equipmentin a secondary serving cell includes the BWP identifier, or the controlsignaling received by the user equipment in the at least one secondaryserving cell includes the BWP identifier, where at least two uplink BWPsare configured for the user equipment in the at least one secondaryserving cell, and a random access channel is configured for each of theat least two uplink BWPs.

According to a tenth aspect, this application provides a network device,where the network device includes a sending module, configured to sendcontrol signaling to user equipment, where the control signaling is usedto trigger the user equipment to perform a random access procedure, andthe control signaling includes or indicates a BWP identifier.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, a BWP corresponding to the BWP identifier is anuplink BWP.

In a possible design, a BWP corresponding to the BWP identifier is a BWPpair including an uplink BWP and a downlink BWP.

According to an eleventh aspect, this application provides userequipment, where the user equipment includes a first receiving module,configured to receive a random access response RAR message sent by anetwork device, where the RAR message includes or indicates a BWPidentifier, and a transmission module, configured to perform uplinktransmission on a first BWP corresponding to the BWP identifier.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, the user equipment further includes a firstactivation module, configured to activate the first BWP before thetransmission module performs uplink transmission on the first BWPcorresponding to the BWP identifier.

In a possible design, the user equipment further includes a secondreceiving module, configured to before the first receiving modulereceives the RAR message sent by the network device, receive controlsignaling sent by the network device, where the control signaling isused to trigger the user equipment to perform a random access procedure,and a sending module, configured to send a random access preamble to thenetwork device on a second BWP.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, the user equipment further includes a secondactivation module, configured to activate the second BWP before thesending module sends the random access preamble to the network device onthe second BWP.

In a possible design, the control signaling includes an identifier ofthe second BWP.

In a possible design, the control signaling received by the userequipment in any serving cell includes the identifier of the second BWP,or the control signaling received by the user equipment in any servingcell includes the identifier of the second BWP, where at least twouplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in the at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In a possible design, the second BWP is a BWP in a first serving cell ofthe user equipment, and the first serving cell is a serving cell usedwhen the user equipment receives the control signaling, or the firstserving cell is a serving cell scheduled by using a second serving cellused when the user equipment receives the control signaling.

In a possible design, the first BWP is an initial active BWP of the userequipment in the first serving cell, or the first BWP is a first activeBWP of the user equipment in the first serving cell, or the first BWP isa default BWP of the user equipment in the first serving cell, or thefirst BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In a possible design, the first BWP and the second BWP are uplink BWPs,and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs.

In a possible design, the first receiving module is specificallyconfigured to receive, on a third BWP, the RAR message sent by thenetwork device, where the third BWP is a downlink BWP, where the thirdBWP is an active BWP in the second serving cell when the user equipmentreceives the control signaling in the first serving cell, or the thirdBWP is a BWP used when the user equipment receives the control signalingin the first serving cell.

In a possible design, the first BWP and the second BWP each are a BWPpair including an uplink BWP and a downlink BWP, and the first BWP andthe second BWP may be a same BWP, or may be different BWPs.

In a possible design, the first receiving module is specificallyconfigured to receive, on the uplink BWP of the second BWP, the RARmessage sent by the network device.

In a possible design, the first receiving module is specificallyconfigured to receive, on a fourth BWP, the RAR message sent by thenetwork device, where the fourth BWP is a BWP pair including an uplinkBWP and a downlink BWP, where the fourth BWP is an active BWP in thesecond serving cell when the user equipment receives the controlsignaling in the first serving cell, or the fourth BWP is a BWP usedwhen the user equipment receives the control signaling in the firstserving cell.

In a possible design, if the fourth BWP is a BWP used when the userequipment receives the control signaling in the first serving cell, theuser equipment further includes a third activation module, configured toafter the sending module sends the random access preamble to the networkdevice on the second BWP, activate the fourth BWP, and deactivate thesecond BWP.

According to a twelfth aspect, this application provides a networkdevice, where the network device includes a first sending module,configured to send a random access response RAR message to userequipment, where the RAR message includes or indicates a BWP identifier,and the BWP identifier corresponds to a first BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, the network device further includes a secondsending module, configured to before the first sending module sends theRAR message to the user equipment, send control signaling to the userequipment, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In a possible design, the control signaling is a physical downlinkcontrol channel order PDCCH order.

In a possible design, the control signaling includes an identifier of asecond BWP.

In a possible design, the second BWP is a BWP in a first serving cell ofthe user equipment, and the first serving cell is a serving cell usedwhen the user equipment receives the control signaling, or the firstserving cell is a serving cell scheduled by using a second serving cellused when the user equipment receives the control signaling.

In a possible design, the first BWP is an initial active BWP of the userequipment in the first serving cell, or the first BWP is a first activeBWP of the user equipment in the first serving cell, or the first BWP isa default BWP of the user equipment in the first serving cell, or thefirst BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In a possible design, the first BWP and the second BWP are uplink BWPs,and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs.

In a possible design, the first sending module is specificallyconfigured to send the RAR message to the user equipment on a third BWP,where the third BWP is a downlink BWP, where the third BWP is an activeBWP in the second serving cell when the user equipment receives thecontrol signaling in the first serving cell, or the third BWP is a BWPused when the user equipment receives the control signaling in the firstserving cell.

In a possible design, the first BWP and the second BWP each are a BWPpair including an uplink BWP and a downlink BWP, and the first BWP andthe second BWP may be a same BWP, or may be different BWPs.

In a possible design, the first sending module is specificallyconfigured to send the RAR message to the user equipment on the uplinkBWP of the second BWP.

In a possible design, the first sending module is specificallyconfigured to send the RAR message to the user equipment on a fourthBWP, where the fourth BWP is a BWP pair including an uplink BWP and adownlink BWP, where the fourth BWP is an active BWP in the secondserving cell when the user equipment receives the control signaling inthe first serving cell, or the fourth BWP is a BWP used when the userequipment receives the control signaling in the first serving cell.

According to a thirteenth aspect, this application provides userequipment, where the user equipment includes a receiving module,configured to receive a radio resource control RRC connectionreconfiguration message sent by a first network device, where the RRCconnection reconfiguration message is included in a first message sentby a second network device to the first network device, and the RRCconnection reconfiguration message is used to indicate the primaryserving cell under the second network device for the user equipment, andindicate an active BWP in the primary serving cell, and an accessmodule, configured to initiate a random access procedure on the activeBWP.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a first BWP identifier, and a BWPcorresponding to the first BWP identifier is the active BWP.

In a possible design, the active BWP includes an uplink BWP and adownlink BWP, and the access module includes a first sending submodule,configured to send a random access preamble to the second network deviceon the uplink BWP in the active BWP, a first receiving submodule,configured to receive, by the user equipment on the downlink BWP in theactive BWP, a random access response RAR message sent by the secondnetwork device, where the RAR message includes an uplink grant UL grant,and a first transmission submodule, configured to perform, by the userequipment, uplink transmission on the uplink BWP in the active BWP,where a physical resource used for the uplink transmission is a physicalresource indicated by the UL grant.

In a possible design, the active BWP is a BWP pair including an uplinkBWP and a downlink BWP, and the access module includes a second sendingsubmodule, configured to send a random access preamble to the secondnetwork device on the uplink BWP of the BWP pair, a second receivingsubmodule, configured to receive, on the downlink BWP of the BWP pair,an RAR message sent by the second network device, where the RAR messageincludes a UL grant, and a second transmission submodule, configured toperform uplink transmission on the uplink BWP of the BWP pair, where aphysical resource used for the uplink transmission is a physicalresource indicated by the UL grant.

In a possible design, the first message is a response message sent bythe second network device after the second network device receives asecond message sent by the first network device, and the second messageincludes at least one of the following information: information about anuplink BWP or a BWP pair activated by the user equipment, informationabout all uplink BWPs or BWP pairs configured for the user equipment,and information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, or the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a fourteenth aspect, this application provides a firstnetwork device, where the first network device includes a receivingmodule, configured to receive a first message sent by a second networkdevice, where the first message includes a radio resource control RRCconnection reconfiguration message, and a first sending module,configured to send the RRC connection reconfiguration message to userequipment, where the RRC connection reconfiguration message is used toindicate the primary serving cell under the second network device forthe user equipment, and indicate an active BWP in the primary servingcell.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a first BWP identifier, and a BWPcorresponding to the first BWP identifier is the active BWP.

In a possible design, the active BWP includes an uplink BWP and adownlink BWP.

In a possible design, the active BWP is a BWP pair including an uplinkBWP and a downlink BWP.

In a possible design, the first network device further includes a secondsending module, configured to before the receiving module receives thefirst message sent by the second network device, send a second messageto the second network device, where the second message includes at leastone of the following information: information about an uplink BWP or aBWP pair activated by the user equipment, information about all uplinkBWPs or BWP pairs configured for the user equipment, and informationabout a logical channel of the user equipment, where the logical channelis a logical channel with a highest priority in all logical channels ofthe user equipment that have to-be-transmitted uplink data, or thelogical channel is all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a fifteenth aspect, this application provides userequipment, where the user equipment includes a first receiving module,configured to receive a radio resource control RRC connectionreconfiguration message sent by a first network device, where the RRCconnection reconfiguration message is included in a first message sentby a second network device to the first network device, and the RRCconnection reconfiguration message is used to indicate the primaryserving cell under the second network device for the user equipment, andindicate an active BWP in the primary serving cell, a sending module,configured to send a random access preamble to the second network deviceon the active BWP, a second receiving module, configured to receive, onthe active BWP, a random access response RAR message sent by the secondnetwork device, where the RAR message includes or indicates a first BWPidentifier, and a transmission module, configured to perform uplinktransmission on a first BWP corresponding to the first BWP identifier.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a second BWP identifier, and a BWPcorresponding to the second BWP identifier is the active BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, the user equipment further includes an activationmodule, configured to activate the first BWP before the transmissionmodule performs uplink transmission on the first BWP corresponding tothe first BWP identifier.

In a possible design, the first BWP is an uplink BWP, the active BWPincludes an uplink BWP and a downlink BWP, and the first BWP and theuplink BWP in the active BWP may be a same BWP, or may be differentBWPs, or the first BWP is a BWP pair including an uplink BWP and adownlink BWP, the active BWP is a BWP pair including an uplink BWP and adownlink BWP, and the first BWP and the active BWP may be a same BWP, ormay be different BWPs.

In a possible design, the first message is a response message sent bythe second network device after the second network device receives asecond message sent by the first network device, and the second messageincludes at least one of the following information: information about anuplink BWP or a BWP pair activated by the user equipment, informationabout all uplink BWPs or BWP pairs configured for the user equipment,and information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, or the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a sixteenth aspect, this application provides a secondnetwork device, where the second network device includes a firstreceiving module, configured to receive, on an active BWP, a randomaccess preamble sent by user equipment, where the random access preambleis sent by the user equipment after the user equipment receives a radioresource control RRC connection reconfiguration message sent by a firstnetwork device, and the RRC connection reconfiguration message is usedto indicate the primary serving cell under the second network device forthe user equipment, and indicate an active BWP in the primary servingcell, and a sending module, configured to send a random access responseRAR message to the user equipment on the active BWP, where the RARmessage includes or indicates a first BWP identifier, and the first BWPidentifier corresponds to a first BWP.

In a possible design, the active BWP is a BWP in common configurationinformation of the primary serving cell, or the RRC connectionreconfiguration message includes a second BWP identifier, and a BWPcorresponding to the second BWP identifier is the active BWP.

In a possible design, the RAR message includes an uplink grant UL grant,and the UL grant includes or indicates the BWP identifier.

In a possible design, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In a possible design, the first BWP is an uplink BWP, the active BWPincludes an uplink BWP and a downlink BWP, and the first BWP and theuplink BWP in the active BWP may be a same BWP, or may be differentBWPs, or the first BWP is a BWP pair including an uplink BWP and adownlink BWP, the active BWP is a BWP pair including an uplink BWP and adownlink BWP, and the first BWP and the active BWP may be a same BWP, ormay be different BWPs.

In a possible design, the second network device further includes asecond receiving module, configured to before the first receiving modulereceives, on the active BWP, the random access preamble sent by the userequipment, receive a second message sent by the first network device,where the second message includes at least one of the followinginformation: information about an uplink BWP or a BWP pair activated bythe user equipment, information about all uplink BWPs or BWP pairsconfigured for the user equipment, and information about a logicalchannel of the user equipment, where the logical channel is a logicalchannel with a highest priority in all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment.

In a possible design, the information about the uplink BWP includes atleast one of the following: an identifier of the uplink BWP, a parameterset of a subcarrier spacing and a cyclic prefix length of the uplinkBWP, and a bandwidth value of the uplink BWP, the information about theBWP pair includes at least one of the following: an identifier of theBWP pair, a parameter set of a subcarrier spacing and a cyclic prefixlength of the BWP pair, and a bandwidth value of the BWP pair, and theinformation about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

According to a seventeenth aspect, user equipment is provided, where theuser equipment includes units or means configured to perform the stepsof any method according to the first aspect.

According to an eighteenth aspect, user equipment is provided, where theuser equipment includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the firstaspect.

According to a nineteenth aspect, user equipment is provided, where theuser equipment includes at least one processing element or chipconfigured to perform any method according to the first aspect, and thechip is applied to the user equipment, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the first aspect.

According to a twentieth aspect, a program is provided, where theprogram is configured to perform any method according to the firstaspect when being executed by a processor.

According to a twenty-first aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the twentieth aspect.

According to a twenty-second aspect, a network device is provided, wherethe network device includes units or means configured to perform thesteps of any method according to the second aspect.

According to a twenty-third aspect, a network device is provided, wherethe network device includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the secondaspect.

According to a twenty-fourth aspect, a network device is provided, wherethe network device includes at least one processing element or chipconfigured to perform any method according to the second aspect, and thechip is applied to the network device, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the second aspect in the claims.

According to a twenty-fifth aspect, a program is provided, where theprogram is configured to perform any method according to the secondaspect when being executed by a processor.

According to a twenty-sixth aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the twenty-fifth aspect.

According to a twenty-seventh aspect, user equipment is provided, wherethe user equipment includes units or means configured to perform thesteps of any method according to the third aspect.

According to a twenty-eighth aspect, user equipment is provided, wherethe user equipment includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the thirdaspect.

According to a twenty-ninth aspect, user equipment is provided, wherethe user equipment includes at least one processing element or chipconfigured to perform any method according to the third aspect, and thechip is applied to the user equipment, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the third aspect.

According to a thirtieth aspect, a program is provided, where theprogram is configured to perform any method according to the thirdaspect when being executed by a processor.

According to a thirty-first aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the thirtieth aspect.

According to a thirty-second aspect, a network device is provided, wherethe network device includes units or means configured to perform thesteps of any method according to the fourth aspect.

According to a thirty-third aspect, a network device is provided, wherethe network device includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the fourthaspect.

According to a thirty-fourth aspect, a network device is provided, wherethe network device includes at least one processing element or chipconfigured to perform any method according to the fourth aspect, and thechip is applied to the network device, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the fourth aspect.

According to a thirty-fifth aspect, a program is provided, where theprogram is configured to perform any method according to the fourthaspect when being executed by a processor.

According to a thirty-sixth aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the thirty-fifth aspect.

According to a thirty-seventh aspect, user equipment is provided, wherethe user equipment includes units or means configured to perform thesteps of any method according to the fifth aspect.

According to a thirty-eighth aspect, user equipment is provided, wherethe user equipment includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the fifthaspect.

According to a thirty-ninth aspect, user equipment is provided, wherethe user equipment includes at least one processing element or chipconfigured to perform any method according to the fifth aspect, and thechip is applied to the user equipment, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the fifth aspect.

According to a fortieth aspect, a program is provided, where the programis configured to perform any method according to the fifth aspect whenbeing executed by a processor.

According to a forty-first aspect, a computer readable storage medium isprovided, where the computer readable storage medium includes theprogram according to the fortieth aspect.

According to a forty-second aspect, a network device is provided, wherethe network device includes units or means configured to perform thesteps of any method according to the sixth aspect.

According to a forty-third aspect, a network device is provided, wherethe network device includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the sixthaspect.

According to a forty-fourth aspect, a network device is provided, wherethe network device includes at least one processing element or chipconfigured to perform any method according to the sixth aspect, and thechip is applied to the network device, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the sixth aspect.

According to a forty-fifth aspect, a program is provided, where theprogram is configured to perform any method according to the sixthaspect when being executed by a processor.

According to a forty-sixth aspect, a computer readable storage medium isprovided, where the computer readable storage medium includes theprogram according to the forty-fifth aspect.

According to a forty-seventh aspect, user equipment is provided, wherethe user equipment includes units or means configured to perform thesteps of any method according to the seventh aspect.

According to a forty-eighth aspect, user equipment is provided, wherethe user equipment includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the seventhaspect.

According to a forty-ninth aspect, user equipment is provided, where theuser equipment includes at least one processing element or chipconfigured to perform any method according to the seventh aspect, andthe chip is applied to the user equipment, the chip includes at leastone communications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the seventh aspect.

According to a fiftieth aspect, a program is provided, where the programis configured to perform any method according to the seventh aspect whenbeing executed by a processor.

According to a fifty-first aspect, a computer readable storage medium isprovided, where the computer readable storage medium includes theprogram according to the fiftieth aspect.

According to a fifty-second aspect, a network device is provided, wherethe network device includes units or means configured to perform thesteps of any method according to the eighth aspect.

According to a fifty-third aspect, a network device is provided, wherethe network device includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to the eighthaspect.

According to a fifty-fourth aspect, a network device is provided, wherethe network device includes at least one processing element or chipconfigured to perform any method according to the eighth aspect, and thechip is applied to the network device, the chip includes at least onecommunications interface, at least one processor, and at least onememory, the communications interface, the processor, and the memory areinterconnected by using a circuit, and the processor invokes aninstruction stored in the memory to perform the steps of the methodaccording to the eighth aspect.

According to a fifty-fifth aspect, a program is provided, where theprogram is configured to perform any method according to the eighthaspect when being executed by a processor.

According to a fifty-sixth aspect, a computer readable storage medium isprovided, where the computer readable storage medium includes theprogram according to the fifty-fifth aspect.

It can be learned that the user equipment receives the RAR message sentby the network device, where the RAR message includes or indicates theBWP identifier, and the user equipment performs uplink transmission onthe first BWP corresponding to the BWP identifier. In this way, the userequipment can complete the random access procedure based on the BWPidentifier indicated by the network device. The BWP corresponding to theBWP identifier is consistent with the BWP indicated by the UL grant sentby the network device, so that uplink data can be effectivelytransmitted by using the UL grant in the RAR message.

This application further provides a timer handling method and a device,to resolve a prior-art problem that because scenarios in which a timeris started, restarted, or stopped are incomprehensive, a terminal devicemay fail to correctly start, restart, or stop a timer, and therefore theterminal device cannot correctly switch to a default downlink BWP,affecting power consumption reduction of the terminal device.

According to a fifty-seventh aspect, this application provides a timerhandling method, where the method includes receiving, by a terminaldevice, a physical downlink control channel order PDCCH order messagesent by a network device, where a timer of the terminal device isrunning, and the timer is a timer used by the terminal device to switchfrom an active downlink BWP to a default downlink BWP, and starting orrestarting, by the terminal device, the timer.

In a possible design, the PDCCH order message includes an identifier ofthe downlink BWP, and the downlink BWP indicated by the identifier ofthe downlink BWP is not a default downlink BWP.

According to a fifty-eighth aspect, this application provides a timerhandling method, where the method includes receiving, by a terminaldevice, an indication message sent by a network device, where theindication message is used to instruct the terminal device to activateat least one secondary serving cell, and starting or restarting, by theterminal device, a timer associated with the secondary serving cell,where the timer is a timer used by the terminal device to switch from anactive downlink BWP to a default downlink BWP.

In a possible design, the secondary serving cell is in an inactivestate.

In a possible design, before the receiving, by a terminal device, anindication message sent by a network device, the method further includesreceiving, by the terminal device, a radio resource control RRC messagesent by the network device, where the RRC message includes indicationinformation, the indication information is used to instruct to add ormodify the at least one secondary serving cell, the RRC message furtherincludes a first downlink BWP of the secondary serving cell, the firstdownlink BWP is a downlink BWP that is first activated when thesecondary serving cell is activated, and the first downlink BWP is not adefault downlink BWP.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the starting or restarting, by the terminal device, a timerassociated with the secondary serving cell includes instructing, by theterminal device by using a media access control MAC layer of theterminal device, the physical layer of the terminal device to start orrestart the timer associated with the secondary serving cell.

According to a fifty-ninth aspect, a timer handling method is provided,where the method includes receiving, by a terminal device, an indicationmessage sent by a network device, where the indication message is usedto instruct the terminal device to deactivate at least one secondaryserving cell, a timer associated with the secondary serving cell isrunning, and the timer is a timer used by the terminal device to switchfrom an active downlink BWP to a default downlink BWP, and stopping orresetting, by the terminal device, the timer associated with thesecondary serving cell, or stopping and resetting, by the terminaldevice, the timer associated with the secondary serving cell.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the stopping or resetting, by the terminal device, the timerassociated with the secondary serving cell includes instructing, by theterminal device by using a media access control MAC layer of theterminal device, the physical layer of the terminal device to stop orreset the timer associated with the secondary serving cell, or thestopping and resetting, by the terminal device, the timer associatedwith the secondary serving cell includes instructing, by the terminaldevice by using a MAC layer of the terminal device, the physical layerof the terminal device to stop and reset the timer associated with thesecondary serving cell.

According to a sixtieth aspect, a timer handling method is provided,where the method includes determining, by a terminal device, that asecondary serving cell deactivation timer of a secondary serving cellexpires, where the timer associated with the secondary serving cell isrunning, and the timer is a timer used by the terminal device to switchfrom an active downlink BWP to a default downlink BWP, and stopping orresetting, by the terminal device, the timer associated with thesecondary serving cell, or stopping and resetting, by the terminaldevice, the timer associated with the secondary serving cell.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the stopping or resetting, by the terminal device, the timerassociated with the secondary serving cell includes instructing, by theterminal device by using a media access control MAC layer of theterminal device, the physical layer of the terminal device to stop orreset the timer associated with the secondary serving cell, or thestopping and resetting, by the terminal device, the timer associatedwith the secondary serving cell includes instructing, by the terminaldevice by using a MAC layer of the terminal device, the physical layerof the terminal device to stop and reset the timer associated with thesecondary serving cell.

According to a sixty-first aspect, a terminal device is provided, wherethe terminal device includes a receiving module, configured to receive aphysical downlink control channel order PDCCH order message sent by anetwork device, where a timer of the terminal device is running, and thetimer is a timer used by the terminal device to switch from an activedownlink BWP to a default downlink BWP, and a running module, configuredto start or restart the timer.

In a possible design, the PDCCH order message includes an identifier ofthe downlink BWP, and the downlink BWP indicated by the identifier ofthe downlink BWP is not a default downlink BWP.

According to a sixty-second aspect, a terminal device is provided, wherethe terminal device includes a first receiving module, configured toreceive an indication message sent by a network device, where theindication message is used to instruct the terminal device to activateat least one secondary serving cell, and a running module, configured tostart or restart a timer associated with the secondary serving cell,where the timer is a timer used by the terminal device to switch from anactive downlink BWP to a default downlink BWP.

In a possible design, the secondary serving cell is in an inactivestate.

In a possible design, the terminal device further includes a secondreceiving module, configured to before the first receiving modulereceives the indication message sent by the network device, receive aradio resource control RRC message sent by the network device, where theRRC message includes indication information, the indication informationis used to instruct to add or modify the at least one secondary servingcell, the RRC message further includes a first downlink BWP of thesecondary serving cell, the first downlink BWP is a downlink BWP that isfirst activated when the secondary serving cell is activated, and thefirst downlink BWP is not a default downlink BWP.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the running module is specifically configured to instruct, by usinga media access control MAC layer of the terminal device, the physicallayer of the terminal device to start or restart the timer associatedwith the secondary serving cell.

According to a sixty-third aspect, a terminal device is provided, wherethe terminal device includes a receiving module, configured to receivean indication message sent by a network device, where the indicationmessage is used to instruct the terminal device to deactivate at leastone secondary serving cell, a timer associated with the secondaryserving cell is running, and the timer is a timer used by the terminaldevice to switch from an active downlink BWP to a default downlink BWP,and a processing module, configured to stop or reset the timerassociated with the secondary serving cell, or stop and reset, by theterminal device, the timer associated with the secondary serving cell.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the processing module is specifically configured to instruct, byusing a media access control MAC layer of the terminal device, thephysical layer of the terminal device to stop or reset the timerassociated with the secondary serving cell, or instruct, by using a MAClayer of the terminal device, the physical layer of the terminal deviceto stop and reset the timer associated with the secondary serving cell.

According to a sixty-fourth aspect, a terminal device is provided, wherethe terminal device includes a determining module, configured todetermine that a secondary serving cell deactivation timer of asecondary serving cell expires, where the timer associated with thesecondary serving cell is running, and the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP, and a processing module, configured to stop or reset thetimer associated with the secondary serving cell, or stop and reset, bythe terminal device, the timer associated with the secondary servingcell.

In a possible design, the timer associated with the secondary servingcell is a timer maintained by a physical layer of the terminal device,and the processing module is specifically configured to instruct, byusing a media access control MAC layer of the terminal device, thephysical layer of the terminal device to stop or reset the timerassociated with the secondary serving cell, or instruct, by using a MAClayer of the terminal device, the physical layer of the terminal deviceto stop and reset the timer associated with the secondary serving cell.

According to a sixty-fifth aspect, a terminal device is provided, wherethe terminal device includes units or means configured to perform thesteps of any method according to the fifty-seventh aspect.

According to a sixty-sixth aspect, a terminal device is provided, wherethe terminal device includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory to perform any method according to thefifty-seventh aspect.

According to a sixty-seventh aspect, a terminal device is provided,where the terminal device includes at least one processing element orchip configured to perform any method according to the fifty-seventhaspect.

According to a sixty-eighth aspect, a program is provided, where theprogram is configured to perform any method according to thefifty-seventh aspect when being executed by a processor.

According to a sixty-ninth aspect, a computer readable storage medium isprovided, where the computer readable storage medium includes theprogram according to the sixty-eighth aspect.

According to a seventieth aspect, a terminal device is provided, wherethe terminal device includes units or means configured to perform thesteps of any method according to the fifty-eighth aspect.

According to a seventy-first aspect, a terminal device is provided,where the terminal device includes a processor and a memory, the memoryis configured to store a program, and the processor invokes the programstored in the memory to perform any method according to the fifty-eighthaspect.

According to a seventy-second aspect, a terminal device is provided,where the terminal device includes at least one processing element orchip configured to perform any method according to the fifty-eighthaspect.

According to a seventy-third aspect, a program is provided, where theprogram is configured to perform any method according to thefifty-eighth aspect when being executed by a processor.

According to a seventy-fourth aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the seventy-third aspect.

According to a seventy-fifth aspect, a terminal device is provided,where the terminal device includes units or means configured to performthe steps of any method according to the fifty-ninth aspect.

According to a seventy-sixth aspect, a terminal device is provided,where the terminal device includes a processor and a memory, the memoryis configured to store a program, and the processor invokes the programstored in the memory to perform any method according to the fifty-ninthaspect.

According to a seventy-seventh aspect, a terminal device is provided,where the terminal device includes at least one processing element orchip configured to perform any method according to the fifty-ninthaspect.

According to a seventy-eighth aspect, a program is provided, where theprogram is configured to perform any method according to the fifty-ninthaspect when being executed by a processor.

According to a seventy-ninth aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the seventy-eighth aspect.

According to an eightieth aspect, a terminal device is provided, wherethe terminal device includes units or means configured to perform thesteps of any method according to the sixtieth aspect.

According to an eighty-first aspect, a terminal device is provided,where the terminal device includes a processor and a memory, the memoryis configured to store a program, and the processor invokes the programstored in the memory to perform any method according to the sixtiethaspect.

According to an eighty-second aspect, a terminal device is provided,where the terminal device includes at least one processing element orchip configured to perform any method according to the sixtieth aspect.

According to an eighty-third aspect, a program is provided, where theprogram is configured to perform any method according to the sixtiethaspect when being executed by a processor.

According to an eighty-fourth aspect, a computer readable storage mediumis provided, where the computer readable storage medium includes theprogram according to the eighty-third aspect.

It can be learned that in the foregoing aspects, the terminal devicereceives the PDCCH order message sent by the network device, where thetimer of the terminal device is running, and the timer is a timer usedby the terminal device to switch from an active downlink BWP to adefault downlink BWP, and the terminal device starts or restarts thetimer. Therefore, when the timer of the terminal device is running,after the PDCCH order message sent by the network device is received, itis considered whether the timer is to be started or restarted. In thisway, an operating scenario of the timer is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a schematic diagram of an application scenario according toan embodiment of this application;

FIG. 1b is a schematic diagram of another application scenario accordingto an embodiment of this application;

FIG. 2 is a signaling diagram of an application scenario according to anembodiment of this application;

FIG. 3 is a signaling diagram 1 of a contention free random accessprocedure according to an embodiment of this application;

FIG. 4 is a signaling diagram 2 of a contention free random accessprocedure according to an embodiment of this application;

FIG. 5 is a signaling diagram 3 of a contention free random accessprocedure according to an embodiment of this application;

FIG. 6 is a schematic flowchart of a random access method according toan embodiment of the present invention;

FIG. 7 is a signaling diagram of a random access method according to anembodiment of the present invention;

FIG. 8 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 9 is a signaling diagram 1 of another random access methodaccording to an embodiment of the present invention;

FIG. 10 is a signaling diagram 2 of another random access methodaccording to an embodiment of the present invention;

FIG. 11 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 12 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 13 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 14 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 15 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 16 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 17 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 18 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 19 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 20 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 21 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 22 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 23 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 24 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 25 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 26 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 27 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 28 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 29 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 30 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 31 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 32 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 33 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 34 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 35 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 36 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 37 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 38 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 39 is a signaling diagram of another random access method accordingto an embodiment of the present invention;

FIG. 40 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 41 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 42 is a signaling diagram 1 of another random access methodaccording to an embodiment of the present invention;

FIG. 43 is a signaling diagram 2 of another random access methodaccording to an embodiment of the present invention;

FIG. 44 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 45 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 46 is signaling of another random access method according to anembodiment of the present invention;

FIG. 47 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 48 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 49 is signaling of another random access method according to anembodiment of the present invention;

FIG. 5 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention;

FIG. 51 is a schematic structural diagram of user equipment according toan embodiment of this application;

FIG. 52 is a schematic structural diagram of a network device accordingto an embodiment of this application;

FIG. 53 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 54 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 55 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 56 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 57 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 58 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 59 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 60 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 61 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 62 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 63 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 64 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 65 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application;

FIG. 66 is a schematic structural diagram of another network deviceaccording to an embodiment of this application;

FIG. 67 is a schematic diagram of an application scenario according toan embodiment of this application;

FIG. 68 is a schematic flowchart of a timer handling method according toan embodiment of the present invention;

FIG. 69 is a signaling diagram of a timer handling method according toan embodiment of the present invention;

FIG. 70 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention;

FIG. 71 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention;

FIG. 72 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention;

FIG. 73 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention;

FIG. 74 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention;

FIG. 75 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention;

FIG. 76 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 77 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 78 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 79 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 80 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 81 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 82 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application; and

FIG. 83 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The embodiments of this application are applied to a 5G communicationssystem or another system that may occur in the future. For ease ofunderstanding by a person skilled in the art, the following describessome terms in this application. It should be noted that a name of anetwork device and a name of a terminal may change when the solutions inthe embodiments of this application are applied to the 5G system oranother system that may occur in the future, but this does not affectimplementation of the solutions in the embodiments of this application.

(1) User equipment, also referred to as a terminal or a terminal device,is a device providing a user with voice and/or data connectivity, forexample, a handheld device or an in-vehicle device with a wirelessconnection function. Common user equipment includes, for example, amobile phone, a tablet computer, a notebook computer, a palmtopcomputer, a mobile Internet device (MID), and a wearable device, wherethe wearable device is, for example, a smartwatch, a smart band, or apedometer.

(2) A network device, also referred to as a radio access network (RAN)device, is a device for connecting user equipment to a wireless network.There are network devices of various communication standards. Forexample, the network devices include but are not limited to a basestation, an evolved NodeB (evolved Node B, eNB), a radio networkcontroller (radio network controller, RNC), a NodeB (Node B, NB), anetwork device controller (BSC), a network device transceiver station(BTS), a home network device (for example, a home evolved NodeB or ahome Node B, HNB), a baseband unit (BBU), a relay station, adistribution unit (distribute unit, DU) of the base station, a centralunit (CU) of the base station, and the like.

(3) In terms of a bandwidth part (BWP), when bandwidth of a cell iswide, user equipment may operate only on a part of bandwidth of thecell. Each part of bandwidth of the cell is referred to as one BWP.

(4) There are network devices of various frequency standards. Forexample, the network devices include but are not limited to alow-frequency network device and a high-frequency network device.

(5) “A plurality of” means two or more, and another quantifier issimilar to this. The term “and/or” describes an association relationshipbetween associated objects and represents that three relationships mayexist. For example, A and/or B may represent the following three cases:Only A exists, both A and B exist, and only B exists. The character “/”usually indicates an “or” relationship between the associated objects.

FIG. 1a is a schematic diagram of an application scenario according toan embodiment of this application. A networking architecture shown inFIG. 1a mainly includes a network device 01 and user equipment 02. Thenetwork device 01 may communicate with the user equipment 02. FIG. 1b isa schematic diagram of another application scenario according to anembodiment of this application. A networking architecture shown in FIG.1b mainly includes a network device 03, a network device 04, and userequipment 05. The user equipment 05 needs to be handed over from thenetwork device 03 to the network device 04.

In this application, on a broadband carrier, a network device mayconfigure at least one downlink BWP and at least one uplink BWP for oneuser equipment. Each downlink BWP has one BWP identifier, and eachuplink BWP has one BWP identifier. FIG. 2 is a schematic diagram of aBWP according to an embodiment of this application. Each BWP may occupyat least one physical resource block (PRB). One BWP supports onephysical-layer parameter set of a subcarrier spacing and a cyclic prefixlength. The parameter set includes subcarrier spacing configurationinformation, cyclic prefix length configuration information, and thelike. Parameter sets supported by different BWPs may be the same ordifferent.

In a first version of 5G, one user equipment has only one activedownlink BWP and only one active uplink BWP at any moment in one servingcell. However, the user equipment may dynamically perform BWP switching.In other words, the user equipment may deactivate a BWP in an activestate, and then the user equipment activates a BWP in an inactive state,to complete BWP switching. Specifically, in the prior art, a networkdevice dynamically controls, by using downlink control information(DCI), user equipment to switch between different configured BWPs. Forexample, the network device schedules downlink transmission DCI tocontrol the user equipment to switch between downlink BWPs.Specifically, the network device sends DCI to the user equipment. TheDCI is DCI for downlink transmission scheduling, and the DCI includes aBWP identifier. Then the user equipment activates a downlink BWPcorresponding to the BWP identifier, and the user equipment may receive,on the downlink BWP, a physical downlink shared channel (PDSCH)scheduled by using the DCI. For another example, the network deviceschedules uplink transmission DCI to control the user equipment toswitch between uplink BWPs. Specifically, the network device sends DCIto the user equipment. The DCI is DCI for uplink transmissionscheduling, and the DCI includes a BWP identifier. Then the userequipment activates an uplink BWP corresponding to the BWP identifier,and the user equipment may transmit, on the uplink BWP, a PUSCHscheduled by using the DCI.

One user equipment may have a plurality of services. Services with asame quality of service (QoS) requirement may be mapped to a same dataradio bearer for transmission. Services with different QoS requirementsneed to be mapped to different data radio bearers for transmission, andthe services need to be transmitted by using uplink grants (UL grant).During transmission of each of the services with different QoSrequirements, a UL grant corresponding to the service needs to bedetermined. The UL grant has configuration information corresponding tothe QoS requirement of the service, and the configuration informationincludes the foregoing parameter set and/or a transmission time length.

A network device configures a mapping relationship between a logicalchannel corresponding to a data radio bearer and configurationinformation for user equipment, where the configuration informationincludes the foregoing parameter set and/or a transmission time length,to ensure that a data packet on each data radio bearer can betransmitted by using a suitable UL grant. The suitable UL grant hasconfiguration information that matches a QoS requirement of the datapacket. Specifically, the network device allocates a UL grant to theuser equipment. Only when the user equipment determines that theforegoing parameter set and/or a transmission time length indicated bythe UL grant match or matches a parameter set and/or a transmission timelength of a logical channel, the user equipment can transmit data of thelogical channel by using the UL grant.

In addition, a carrier aggregation function may be configured for aterminal device, and the terminal device is connected to one primaryserving cell (pCell) and at least one secondary serving cell (SCell).There are at least four secondary serving cells. Carrier aggregationmeans aggregating at least two component carriers (CC), to provide widertransmission bandwidth for the terminal. The terminal deviceadds/modifies/deletes a secondary serving cell by using a radio resourcecontrol (RRC) connection reconfiguration message. Anactivation/deactivation mechanism for a secondary serving cell isprovided to better manage power consumption of carrier aggregation. Asecondary serving cell is activated/deactivated by using a media accesscontrol (MAC) control element (CE). The MAC CE may be configured toactivate or deactivate at least one secondary serving cell. In addition,deactivation of a secondary serving cell may be controlled by using asecondary serving cell deactivation timer. Specifically, when asecondary serving cell deactivation timer expires, a secondary servingcell corresponding to the secondary serving cell deactivation timer isautomatically deactivated. It can be learned that when the terminaldevice successfully adds a secondary serving cell, the secondary servingcell is configured by the network device for the terminal device, butthe secondary serving cell is still in an inactive state, and theterminal device further needs to activate the secondary serving cellaccording to an activate command. The terminal device can perform datacommunication only on an active secondary serving cell.

One user equipment may transmit data on one carrier by using a pluralityof UL grants. When a carrier aggregation function is configured for theuser equipment, the user equipment may also transmit data on differentcarriers by using a plurality of UL grants.

In the prior art, different BWPs may have different configurationinformation, and it can be learned that the configuration informationincludes a parameter set and/or a transmission time length. Theparameter set is a parameter set of a subcarrier spacing and a cyclicprefix length. In a contention free random access procedure,configuration information of an uplink BWP used by the user equipment tosend a message 1 to the network device may not match configurationinformation required when the user equipment sends uplink data to thenetwork device. Therefore, the user equipment cannot send the uplinkdata by using a UL grant that is in an RAR message and that correspondsto the uplink BWP, wasting the UL grant that is in the RAR message andthat corresponds to the uplink BWP.

For example, a primary serving cell and one secondary serving cell areconfigured for the user equipment, and an uplink timing advance used onan uplink of the secondary serving cell is different from an uplinktiming advance used on an uplink of the primary serving cell. Therefore,if the user equipment needs to transmit uplink data in the secondaryserving cell, the user equipment first needs to implement uplinksynchronization in the secondary serving cell through random access. Inthis case, the secondary serving cell and the primary serving cellbelong to different timing advance groups (timing advance group, TAG).In the secondary serving cell, the network device configures two uplinkBWPs and two downlink BWPs for the user equipment, and configuredinitial active BWPs are an uplink BWP 1 and a downlink BWP 1. Aparameter set of a subcarrier spacing and a cyclic prefix length of theuplink BWP 1 is a parameter set A of a subcarrier spacing and a cyclicprefix length, and a parameter set of a subcarrier spacing and a cyclicprefix length of an uplink BWP 2 is a parameter set B of a subcarrierspacing and a cyclic prefix length. FIG. 2 is a signaling diagram of anapplication scenario according to an embodiment of this application. Instep S11, a network device activates, by using a MAC CE, a secondaryserving cell configured for user equipment. In this case, a downlink BWP1 and an uplink BWP 1 of the secondary serving cell are activated. Instep S12, the user equipment sends a buffer status report (BSR) messageto the network device. The BSR message includes or indicates a parameterset that is of a subcarrier spacing and a cyclic prefix length and thatcan be used for to-be-transmitted data, namely, a parameter set B of asubcarrier spacing and a cyclic prefix length. In step S13, the networkdevice determines, based on the BSR message, to use an uplink BWP of thesecondary serving cell to transmit data. In step S14, the network devicesends a physical downlink control channel order (PDCCH order) to theuser equipment. The PDCCH order is used to trigger the user equipment tosend a preamble on the uplink BWP 1 of the secondary serving cell. Instep S15, the user equipment sends the preamble to the network device onthe uplink BWP 1. In step S16, the network device sends an RAR messageto the user equipment. The RAR message includes a UL grant, and the ULgrant is a UL grant corresponding to the uplink BWP 1. However, in thiscase, data of the user equipment needs to be sent to the network deviceon an uplink BWP 2. In this case, configuration information of theuplink BWP 1 does not match configuration information of the uplink BWP2. Therefore, the user equipment cannot transmit data by using the ULgrant in the RAR message, wasting the UL grant in the RAR message.

It should be noted that the terms used in the embodiments of thisapplication may be mutually referenced, and details are not describedagain.

The following first describes a contention free random access procedure.Random access procedures include a contention-based random accessprocedure and a contention free random access procedure, and thecontention free random access procedure is initiated by user equipmentbased on triggering by a network device.

In a first case of the contention free random access procedure, thenetwork device instructs, by using a PDCCH order, the user equipment toinitiate random access. In an example scenario, downlink data on a basestation side needs to be sent to user equipment, but the user equipmentloses uplink synchronization, or a base station needs to schedule userequipment to transmit uplink data in an SCell, but the user equipmenthas not obtained an uplink timing advance of the SCell. FIG. 3 is asignaling diagram 1 of a contention free random access procedureaccording to an embodiment of this application. As shown in FIG. 3, instep S21, a network device sends a PDCCH order to user equipment. ThePDCCH order is used to trigger the user equipment to perform randomaccess, and the PDCCH order includes a preamble and configurationinformation of a physical random access channel (PRACH) corresponding tothe preamble. In this case, downlink data arrives at the user equipment,but the user equipment has not implemented uplink synchronization, orthe user equipment needs to implement uplink synchronization in asecondary serving cell. In step S22, the user equipment sends a preambleto the network device on the PRACH indicated by the PDCCH order. Thepreamble is the preamble allocated in the PDCCH order. In step S23, thenetwork device schedules a random RAR message by using a PDCCH scrambledby using an RA-RNTI. In step S24, the network device sends the RARmessage to the user equipment. The RAR message includes a UL grant. Instep S25, the user equipment transmits uplink data by using the ULgrant, that is, the user equipment sends data or signaling to thenetwork device by using the UL grant.

In a second case of the contention free random access procedure, ahandover is required by the user equipment. FIG. 4 is a signalingdiagram 2 of a contention free random access procedure according to anembodiment of this application. As shown in FIG. 4, in step S31, asource network device sends a handover request to a target networkdevice. In step S32, the target network device sends an acknowledgementmessage to the source network device. The acknowledgement messageincludes an RRC connection reconfiguration message. In step S33, thesource network device sends the RRC connection reconfiguration messageto user equipment. The RRC connection reconfiguration message is used totrigger the user equipment to perform random access, and the RRCconnection reconfiguration message includes a preamble and configurationinformation of a PRACH corresponding to the preamble. In step S34, theuser equipment sends a preamble to the target network device on thePRACH indicated by the RRC connection reconfiguration message. Thepreamble is the preamble allocated in the RRC connection reconfigurationmessage. In step S35, the target network device schedules a random RARmessage by using a PDCCH scrambled by using an RA-RNTI, and the targetnetwork device sends the RAR message to the user equipment. The RARmessage includes a UL grant. In step S36, the user equipment transmitsuplink data by using the UL grant, that is, the user equipment sendsdata or signaling to the target network device by using the UL grant.

In a third case of the contention free random access procedure, dualconnectivity is configured for the user equipment. FIG. 5 is a signalingdiagram 3 of a contention free random access procedure according to anembodiment of this application. As shown in FIG. 5, in step S41, aprimary network device node sends a secondary network device nodeaddition request message to a secondary network device node. In S42, thesecondary network device node sends a secondary network device nodeaddition request acknowledgement message to the primary network devicenode. In S43, the primary network device node sends an RRC connectionreconfiguration message to user equipment. In S44, the user equipmentsends an RRC connection reconfiguration complete message to the primarynetwork device node. In S45, the primary network device node sends thereconfiguration complete message to the secondary network device node.In S46, the user equipment sends a preamble to the secondary networkdevice node on a PRACH indicated by the RRC connection reconfigurationmessage. In S47, the secondary network device node schedules an RARmessage by using a PDCCH scrambled by using an RA-RNTI, and sends theRAR message to the user equipment. In S48, the user equipment transmitsuplink data by using a UL grant.

The following describes the embodiments of this application. First,based on the contention free random access procedure in FIG. 3, in thescenario shown in FIG. 1a , the solutions of the embodiments of thisapplication are as follows:

FIG. 6 is a schematic flowchart of a random access method according toan embodiment of the present invention. As shown in FIG. 6, the methodis specifically as follows:

101. User equipment receives control signaling sent by a network device,where the control signaling is used to trigger the user equipment toperform a random access procedure, and the control signaling includes orindicates a BWP identifier.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the BWP identifier, or thecontrol signaling received by the user equipment in any serving cellincludes the BWP identifier, where at least two uplink BWPs areconfigured for the user equipment in at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs, or the control signaling received by the user equipmentin a secondary serving cell includes the BWP identifier, or the controlsignaling received by the user equipment in at least one secondaryserving cell includes the BWP identifier, where at least two uplink BWPsare configured for the user equipment in the at least one secondaryserving cell, and a random access channel is configured for each of theat least two uplink BWPs.

In this embodiment, the network device configures at least one BWP forthe user equipment in the secondary serving cell, and a PRACH resourceis configured for each of the at least one BWP. In this case, the userequipment operates in a serving cell. In other words, the user equipmentcommunicates with the network device in a serving cell. Optionally, theuser equipment operates in a secondary serving cell, and the secondaryserving cell and a primary serving cell of the user equipment belong todifferent TAGs, or the user equipment operates in a primary servingcell.

The network device sends the control signaling to the user equipment.The control signaling may be signaling or a signal, and the controlsignaling is used to trigger the user equipment to perform a randomaccess procedure. In addition, the control signaling includes the BWPidentifier, or the control signaling indicates the BWP identifier.

In addition, the user equipment may determine, by using the followingmethods, whether the received control signaling includes a BWPidentifier. Cross-carrier scheduling may be unavailable for the userequipment, or cross-carrier scheduling may be available for the userequipment.

In a first manner, the control signaling received by the user equipmentin any serving cell always includes a BWP identifier.

In a second manner, at least two uplink BWPs are configured for the userequipment in any secondary serving cell, and a random access channel isconfigured for each of the at least two uplink BWPs. In this case, thecontrol signaling received by the user equipment in any serving cellincludes a BWP identifier. Optionally, if the terminal device operatesin a secondary serving cell, the secondary serving cell and a primaryserving cell of the terminal device belong to different TAGs. At leasttwo uplink BWPs are configured for the user equipment in any secondaryserving cell, and a random access channel is configured for only one ofthe at least two uplink BWPs. In this case, the control signalingreceived by the user equipment in any serving cell includes no BWPidentifier. Optionally, if the terminal device operates in a secondaryserving cell, the secondary serving cell and a primary serving cell ofthe terminal device belong to different TAGs.

In a third manner, if the terminal device operates in a primary servingcell, the control signaling received by the user equipment in theprimary serving cell includes no BWP identifier. If the terminal deviceoperates in a secondary serving cell, the control signaling received bythe user equipment in the secondary serving cell includes a BWPidentifier. Optionally, the secondary serving cell and a primary servingcell of the terminal device belong to different TAGs.

In a fourth manner, if the terminal device operates in a primary servingcell, the control signaling received by the user equipment in theprimary serving cell includes no BWP identifier. At least two uplinkBWPs are configured for the user equipment in at least one secondaryserving cell, and a random access channel is configured for each of theat least two uplink BWPs. In this case, the control signaling receivedby the user equipment in the at least one secondary serving cellincludes a BWP identifier. Optionally, the at least one secondaryserving cell and a primary serving cell of the terminal device belong todifferent time TAGs. At least two uplink BWPs are configured for theuser equipment in at least one secondary serving cell, and a randomaccess channel is configured for only one of the at least two uplinkBWPs. In this case, the control signaling received by the user equipmentin the at least one secondary serving cell includes a BWP identifier.Optionally, the at least one secondary serving cell and a primaryserving cell of the terminal device belong to different time TAGs.

102. The user equipment initiates a random access procedure based on thecontrol signaling.

In this embodiment, the user equipment performs random access to thenetwork device based on the BWP identifier.

FIG. 7 is a signaling diagram of a random access method according to anembodiment of the present invention. As shown in FIG. 7, the method isspecifically as follows:

S51. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes or indicatesa BWP identifier.

S52. The user equipment initiates a random access procedure based on thecontrol signaling.

Herein, step 101 in FIG. 6 is implemented in step S51. For S52, refer tostep 102 in FIG. 6. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, where the control signaling is used totrigger the user equipment to perform a random access procedure, and thecontrol signaling includes or indicates the BWP identifier, and the userequipment initiates the random access procedure based on the controlsignaling. In this way, the user equipment can complete the randomaccess procedure based on the BWP identifier indicated by the networkdevice. A BWP corresponding to the BWP identifier is consistent with aBWP indicated by a UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in an RARmessage.

FIG. 8 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG. 8,the method is specifically as follows:

201. User equipment receives a PDCCH order sent by a network device,where the PDCCH order is used to trigger the user equipment to perform arandom access procedure, and the PDCCH order includes or indicates a BWPidentifier.

In this embodiment, the network device configures at least one uplinkBWP for the user equipment in the secondary serving cell, and a PRACHresource is configured for each of the at least one uplink BWP. In thiscase, the user equipment operates in a serving cell. In other words, theuser equipment communicates with the network device in a serving cell.Optionally, the user equipment operates in a secondary serving cell, andthe secondary serving cell and a primary serving cell of the userequipment belong to different TAGs, or the user equipment operates in aprimary serving cell.

The network device sends the PDCCH order to the user equipment. ThePDCCH order is used to trigger the user equipment to perform a randomaccess procedure. In addition, the PDCCH order includes the BWPidentifier, or the PDCCH order indicates the BWP identifier. Moreover, aBWP corresponding to the BWP identifier may be an uplink BWP, a downlinkBWP, or a pair of an uplink BWP and a downlink BWP.

In this case, the user equipment has an active downlink BWP in a servingcell, and the user equipment may receive the PDCCH order on the downlinkBWP of the current serving cell. Alternatively, the user equipment mayreceive the PDCCH order on a downlink BWP of another serving cell usedto schedule a current serving cell. In this case, the PDCCH orderincludes a cell index of the current serving cell.

202. The user equipment initiates a random access procedure on the BWPcorresponding to the BWP identifier.

In this embodiment, the user equipment initiates the random accessprocedure to the network device on the BWP corresponding to the BWPidentifier.

In an optional implementation, there are the following implementationsof step 202:

In a first implementation of step 202, the BWP corresponding to the BWPidentifier is an uplink BWP, and step 202 specifically includes thefollowing steps:

2021 a. The user equipment sends a random access preamble to the networkdevice on the uplink BWP.

2022 a. The user equipment receives a first RAR message sent by thenetwork device, where the first RAR message includes a first UL grant.

2023 a. The user equipment performs uplink transmission on the uplinkBWP, where a physical resource used for the uplink transmission is aphysical resource indicated by the first UL grant.

In this embodiment, the BWP of the BWP identifier protected or indicatedby control signaling is an uplink BWP. In this case, after step 101, theuser equipment sends the random access preamble to the network device onthe uplink BWP. Then the network device sends the first RAR message tothe user equipment, where the first RAR message includes the first ULgrant, and the first UL grant is a UL grant corresponding to the uplinkBWP. Then the user equipment sends data or signaling to the networkdevice on the uplink BWP by using the physical resource indicated by thefirst UL grant.

In a second implementation of step 202, the BWP corresponding to the BWPidentifier is a BWP pair including an uplink BWP and a downlink BWP, andstep 202 specifically includes the following steps:

2021 b. The user equipment sends a random access preamble to the networkdevice on the uplink BWP of the BWP.

2022 b. The user equipment receives a second RAR message sent by thenetwork device, where the second RAR message includes a second UL grant.

2023 b. The user equipment performs transmission on the uplink BWP ofthe BWP, where a physical resource used for the transmission is aphysical resource indicated by the second UL grant.

In an optional implementation, before step 202, the method may furtherinclude step 203:

203. The user equipment activates the BWP corresponding to the BWPidentifier.

In this embodiment, there are three cases as to whether the userequipment needs to activate the BWP corresponding to the BWP identifier.

In a first case, when the user equipment receives the PDCCH order, ifthe user equipment has no active BWP in the current serving cell, theuser equipment needs to activate the BWP corresponding to the BWPidentifier.

In a second case, when the user equipment receives the PDCCH order, ifan active uplink BWP of the user equipment in a current first servingcell is another BWP, the user equipment switches to the BWPcorresponding to the BWP identifier, in other words, the user equipmentdeactivates the another BWP, and activates the BWP corresponding to theBWP identifier.

In a third case, when the user equipment receives the PDCCH order, if anactive uplink BWP of the user equipment in a current first serving cellis the BWP corresponding to the BWP identifier, the user equipment doesnot need to perform BWP switching.

In this step, in the first case or the second case, the user equipmentneeds to activate the BWP corresponding to the BWP identifier.

In this embodiment, the BWP of the BWP identifier protected or indicatedby control signaling is a BWP pair including an uplink BWP and adownlink BWP. In this case, after step 101, the user equipment sends therandom access preamble to the network device on the uplink BWP of theBWP. The network device receives the second RAR message from the userequipment, where the second RAR message includes the second UL grant,and the second UL grant is a UL grant corresponding to the uplink BWP ofthe BWP. The user equipment sends data or signaling to the networkdevice on the uplink BWP of the BWP by using the physical resourceindicated by the second UL grant.

FIG. 9 is a signaling diagram 1 of another random access methodaccording to an embodiment of the present invention. As shown in FIG. 9,the method is specifically as follows:

S61 a. A network device sends a PDCCH order to user equipment, where thePDCCH order is used to trigger the user equipment to perform a randomaccess procedure, the PDCCH order includes or indicates a BWPidentifier, and a BWP corresponding to the BWP identifier is an uplinkBWP.

S62 a. The user equipment sends a random access preamble to the networkdevice on the uplink BWP.

S63 a. The network device sends a first RAR message to the userequipment, where the first RAR message includes a first UL grant.

S64 a. The user equipment performs uplink transmission on the uplinkBWP, where a physical resource used for the uplink transmission is aphysical resource indicated by the first UL grant.

Herein, steps S61 a to S64 a are step 201 and the first implementationof step 202 in FIG. 8. Details are not described again.

FIG. 10 is a signaling diagram 2 of another random access methodaccording to an embodiment of the present invention. As shown in FIG.10, the method is specifically as follows:

S61 b. A network device sends a PDCCH order to user equipment, where thePDCCH order is used to trigger the user equipment to perform a randomaccess procedure, the PDCCH order includes or indicates a BWPidentifier, and a BWP corresponding to the BWP identifier is a BWP pairincluding an uplink BWP and a downlink BWP.

S62 b. The user equipment sends a random access preamble to the networkdevice on the uplink BWP of the BWP.

S63 b. The network device sends a second RAR message to the userequipment, where the second RAR message includes a second UL grant.

S64 b. The user equipment performs transmission on the uplink BWP of theBWP, where a physical resource used for the transmission is a physicalresource indicated by the second UL grant.

Herein, steps S61 b to S64 b are step 201 and the second implementationof step 202 in FIG. 8. Details are not described again.

In this embodiment, the user equipment receives control signaling sentby the network device, where the control signaling is used to triggerthe user equipment to perform a random access procedure, and the controlsignaling includes or indicates the BWP identifier, and the userequipment initiates a random access procedure based on the controlsignaling. In this way, the user equipment can complete the randomaccess procedure based on the BWP identifier indicated by the networkdevice. The BWP corresponding to the BWP identifier is consistent with aBWP indicated by a UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in an RARmessage.

FIG. 11 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.11, the method is specifically as follows:

301. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes or indicatesa BWP identifier.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, a BWP is an uplink BWP, or a BWPcorresponding to the BWP identifier is a BWP pair including an uplinkBWP and a downlink BWP.

For the method provided in this embodiment, refer to the methods in FIG.6 to FIG. 10. Details are not described again.

FIG. 12 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.12, the method is specifically as follows:

401. User equipment receives an RAR message sent by a network device,where the RAR message includes or indicates a BWP identifier.

In this embodiment, in a contention free random access procedure, thenetwork device sends the RAR message to the user equipment. The RARmessage includes the BWP identifier, or the RAR message indicates theBWP identifier.

402. The user equipment performs uplink transmission on a first BWPcorresponding to the BWP identifier.

In this embodiment, the user equipment sends data or signaling to thenetwork device on the first BWP corresponding to the BWP identifier.

FIG. 13 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 13, themethod is specifically as follows:

S71. A network device sends an RAR message to user equipment, where theRAR message includes or indicates a BWP identifier.

S72. The user equipment performs uplink transmission on a first BWPcorresponding to the BWP identifier.

Herein, step 401 in FIG. 12 is implemented in step S71. For S72, referto step 402 in FIG. 12. Details are not described again.

In this embodiment, the user equipment receives the RAR message sent bythe network device, where the RAR message includes or indicates the BWPidentifier, and the user equipment performs uplink transmission on thefirst BWP corresponding to the BWP identifier. In this way, the userequipment can complete a random access procedure based on the BWPidentifier indicated by the network device. The BWP corresponding to theBWP identifier is consistent with a BWP indicated by a UL grant sent bythe network device, so that uplink data can be effectively transmittedby using the UL grant in the RAR message.

FIG. 14 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.14, the method is specifically as follows:

501. User equipment receives control signaling sent by a network device,where the control signaling is used to trigger the user equipment toperform a random access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

In this embodiment, at least one serving cell is configured for the userequipment, and the at least one serving cell includes the first servingcell. The user equipment receives, in the first serving cell, thecontrol signaling sent by the network device.

In this embodiment, the network device configures at least one BWP forthe user equipment in the first serving cell, and PRACH resources areconfigured only for some of the at least one BWP. In this case, the userequipment operates in the first serving cell. In other words, the userequipment communicates with the network device in the first servingcell. Optionally, the user equipment operates in a secondary servingcell, and the secondary serving cell and a primary serving cell of theuser equipment belong to different TAGs, or the user equipment operatesin a primary serving cell.

The network device sends the control signaling to the user equipment.The control signaling may be signaling or a signal, and the controlsignaling is used to trigger the user equipment to perform a randomaccess procedure. In addition, the control signaling includes the BWPidentifier, or the control signaling indicates the BWP identifier.Further, the control signaling is a PDCCH order, and the BWPcorresponding to the BWP identifier may be an uplink BWP, a downlinkBWP, or a pair of an uplink BWP and a downlink BWP. In this case, theuser equipment has an active downlink BWP in the first serving cell, andthe user equipment may receive the PDCCH order on the downlink BWP ofthe first serving cell. Alternatively, the user equipment may receivethe PDCCH order on a downlink BWP of a second serving cell used toschedule the first serving cell. In this case, the PDCCH order includesa cell index of the current serving cell.

In addition, the user equipment may determine, by using the followingmethods, whether the received control signaling includes a BWPidentifier. Cross-carrier scheduling may be unavailable for the userequipment, or cross-carrier scheduling may be available for the userequipment.

In a first manner, the control signaling received by the user equipmentin any serving cell always includes an identifier of a second BWP.

In a second manner, at least two uplink BWPs are configured for the userequipment in any secondary serving cell, and a random access channel isconfigured for each of the at least two uplink BWPs. In this case, thecontrol signaling received by the user equipment in any serving cellincludes an identifier of a second BWP. Optionally, if the terminaldevice operates in a secondary serving cell, the secondary serving celland a primary serving cell of the terminal device belong to differentTAGs. At least two uplink BWPs are configured for the user equipment inany secondary serving cell, and a random access channel is configuredfor only one of the at least two uplink BWPs. In this case, the controlsignaling received by the user equipment in any serving cell includes noidentifier of a second BWP. Optionally, if the terminal device operatesin a secondary serving cell, the secondary serving cell and a primaryserving cell of the terminal device belong to different TAGs.

In a third manner, if the terminal device operates in a primary servingcell, the control signaling received by the user equipment in theprimary serving cell includes no identifier of a second BWP. If theterminal device operates in a secondary serving cell, the controlsignaling received by the user equipment in the secondary serving cellincludes an identifier of a second BWP. Optionally, the secondaryserving cell and a primary serving cell of the terminal device belong todifferent TAGs.

In a fourth manner, if the terminal device operates in a primary servingcell, the control signaling received by the user equipment in theprimary serving cell includes no identifier of a second BWP. At leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs. In this case, the controlsignaling received by the user equipment in the at least one secondaryserving cell includes an identifier of a second BWP. Optionally, the atleast one secondary serving cell and a primary serving cell of theterminal device belong to different time TAGs. At least two uplink BWPsare configured for the user equipment in at least one secondary servingcell, and a random access channel is configured for only one of the atleast two uplink BWPs. In this case, the control signaling received bythe user equipment in the at least one secondary serving cell includesan identifier of a second BWP. Optionally, the at least one secondaryserving cell and a primary serving cell of the terminal device belong todifferent time TAGs.

502. The user equipment activates the second BWP.

In this embodiment, there are three cases as to whether the userequipment needs to activate the second BWP.

In a first case, when the user equipment receives the PDCCH order, ifthe user equipment has no active BWP in the current serving cell, theuser equipment needs to activate the second BWP.

In a second case, when the user equipment receives the PDCCH order, ifan active uplink BWP of the user equipment in the current first servingcell is another BWP, the user equipment switches to the second BWP, inother words, the user equipment deactivates the another BWP, andactivates the second BWP.

In a third case, when the user equipment receives the PDCCH order, if anactive uplink BWP of the user equipment in the current first servingcell is the second BWP, the user equipment does not need to perform BWPswitching.

In this step, in the first case or the second case, the user equipmentneeds to activate the second BWP.

503. The user equipment sends a random access preamble to the networkdevice on the second BWP.

In this embodiment, the user equipment sends the random access preambleto the network device on the second BWP.

504. The user equipment receives an RAR message sent by the networkdevice, where the RAR message includes a UL grant, and the UL grantincludes or indicates a BWP identifier.

In this embodiment, the network device sends the RAR message to the userequipment. The RAR message includes the UL grant, and the RAR messageincludes the BWP identifier, or the RAR message indicates the BWPidentifier. Specifically, the UL grant in the RAR message includes theBWP identifier, or the UL grant in the RAR message indicates the BWPidentifier. Alternatively, the BWP identifier is directly included inthe RAR message as an information field in the RAR message.

In an optional implementation, there are the following implementationsof step 504:

In a first implementation of step 504, a first BWP and the second BWPare uplink BWPs, and the first BWP and the second BWP may be a same BWP,or may be different BWPs. Step 504 specifically includes receiving, bythe user equipment on a third BWP, the RAR message sent by the networkdevice, where the third BWP is a downlink BWP, where the third BWP is anactive BWP in the second serving cell when the user equipment receivesthe control signaling in the first serving cell, or the third BWP is aBWP used when the user equipment receives the control signaling in thefirst serving cell.

In this embodiment, the first BWP is an uplink BWP, and the second BWPis also an uplink BWP. In this case, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 504, the userequipment receives, on the third BWP, the RAR message sent by thenetwork device, where the third BWP is a downlink BWP.

In a second implementation of step 504, a first BWP and the second BWPeach are a BWP pair including an uplink BWP and a downlink BWP, and thefirst BWP and the second BWP may be a same BWP, or may be differentBWPs. Step 504 specifically includes receiving, by the user equipment onthe uplink BWP of the second BWP, the RAR message sent by the networkdevice.

In this embodiment, the first BWP is a BWP pair including an uplink BWPand a downlink BWP, and the second BWP is a BWP pair including an uplinkBWP and a downlink BWP. In addition, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 504, the userequipment receives, on the uplink BWP of the second BWP, the RAR messagesent by the network device.

In a third implementation of step 504, the user equipment receives, on afourth BWP, the RAR message sent by the network device, where the fourthBWP is a BWP pair including an uplink BWP and a downlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 503, the method further includes step 507: The user equipmentactivates the fourth BWP, and deactivates the second BWP.

In this embodiment, the fourth BWP is provided. Optionally, the fourthBWP is a BWP pair including an uplink BWP and a downlink BWP. The userequipment first needs to switch to the fourth BWP, in other words, theuser equipment activates the fourth BWP, and deactivates the second BWP.Then the user equipment may receive, on the fourth BWP, the RAR messagesent by the network device.

505. The user equipment activates the first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is the identifier of the secondBWP, the first BWP corresponding to the BWP is the second BWP, and itmay be determined that the UL grant included in the RAR message is a ULgrant corresponding to the second BWP of the user equipment in the firstserving cell. In this case, the user equipment does not need to performBWP switching, in other words, the first BWP is in an active state, andthe user equipment does not need to further activate the first BWP. Inthis case, the user equipment may send data or signaling to the networkdevice on the second BWP of the first serving cell based on the UL grantin the RAR message.

In a second case, if the BWP identifier is not the identifier of thesecond BWP, the first BWP corresponding to the BWP is different from thesecond BWP, and it may be determined that the UL grant included in theRAR message is a UL grant corresponding to the first BWP of the userequipment in the first serving cell. In this case, the user equipmentneeds to switch to the first BWP, in other words, deactivate the secondBWP, and activate the first BWP. In this case, the user equipment maysend data or signaling to the network device on the first BWP of thefirst serving cell based on the UL grant in the RAR message.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier. Optionally, the firstBWP is an initial active BWP of the user equipment in the first servingcell, or the first BWP is a first active BWP of the user equipment inthe first serving cell, or the first BWP is a default BWP of the userequipment in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is used by the user equipment to perform random access in the firstserving cell, or the first BWP is a BWP configured by the network devicefor the user equipment, and the first BWP is a BWP used by the userequipment to perform contention free random access in the first servingcell, or the first BWP is a BWP activated when the user equipmentperforms random access, or the first BWP is a BWP activated when theuser equipment performs contention free random access.

The initial active BWP (initial BWP) may be an initial BWP (1) of theuser equipment in an idle mode, or may be an initial BWP (2) configuredby the network device for the user equipment when the user equipment isin a connected mode. For (1), the initial BWP is a BWP configured insystem information indicated by or associated with a cell definingsynchronization signal block (cell defining SS block) of the userequipment in the serving cell. For (2), the initial BWP is a BWPconfigured by the network device in a common configuration informationelement of the serving cell of the user equipment. The initial uplinkbandwidth part may also be referred to as a cell defining uplinkbandwidth part.

The first active BWP (First Active UL BWP) is a first uplink BWP that isof the serving cell of the user equipment and that is also activatedwhen the serving cell is activated, and is configured by the networkdevice in a dedicated configuration information element of the servingcell.

The default BWP is an active uplink BWP to which the user equipmentfalls back after the user equipment has no to-be-transmitted uplink dataand/or no to-be-received downlink data for a period of time, and isconfigured by the network device in a cell-dedicated configurationinformation element of the serving cell. When the first BWP is a BWPactivated when the user equipment performs random access, “randomaccess” herein refers to any one of the following cases:

(1) The user equipment initiates a random access procedure, includingthe following: A MAC entity of the user equipment triggers the randomaccess procedure, an RRC layer of the user equipment triggers the randomaccess procedure, the user equipment receives a PDCCH order sent by thenetwork device and triggers the random access procedure, or the userequipment receives RRC signaling sent by the network device and triggersthe random access procedure. (2) The user equipment starts to perform arandom access procedure. (3) The user equipment starts to open a windowused to monitor a random access response message. (4). The userequipment selects a random access preamble and a random access channel.(5) The user equipment sends a random access preamble. (6) The userequipment completes sending a random access preamble.

506. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, the user equipment sends, on the first BWP indicatedby the network device, data or an instruction to the network device byusing the physical resource indicated by the UL grant in the RARmessage.

FIG. 15 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 15, themethod is specifically as follows:

S81. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

S82. The user equipment activates the second BWP.

S83. The user equipment sends a random access preamble to the networkdevice on the second BWP.

584. The network device sends an RAR message to the user equipment,where the RAR message includes a UL grant, and the UL grant includes orindicates a BWP identifier.

S85. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S86. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 501 to 506 in FIG. 14 are implemented in steps S81 to S86.Details are not described again.

In this embodiment, the network device sends the control signaling tothe user equipment, where the control signaling is used to trigger theuser equipment to perform a random access procedure, and the controlsignaling includes the identifier of the second BWP, the user equipmentreceives the RAR message sent by the network device, where the RARmessage includes or indicates the BWP identifier, and the user equipmentperforms uplink transmission on the first BWP corresponding to the BWPidentifier. In this way, the user equipment can send the random accesspreamble to the network device based on the identifier that is of thesecond BWP and that is indicated by the network device. The first BWPcorresponding to the BWP identifier is consistent with the BWP indicatedby the UL grant sent by the network device, so that uplink data can beeffectively transmitted by using the UL grant in the RAR message.

FIG. 16 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.16, the method is specifically as follows:

601. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

602. The network device sends an RAR message to the user equipment,where the RAR message includes or indicates a BWP identifier, and theBWP identifier corresponds to a first BWP.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In an optional implementation, the first BWP and the second BWP areuplink BWPs, and the first BWP and the second BWP may be a same BWP, ormay be different BWPs.

In an optional implementation, step 602 specifically includes sending,by the network device, the RAR message to the user equipment on a thirdBWP, where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In an optional implementation, the first BWP and the second BWP each area BWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step 602specifically includes sending, by the network device, the RAR message tothe user equipment on the uplink BWP of the second BWP.

In an optional implementation, step 602 specifically includes sending,by the network device, the RAR message to the user equipment on a fourthBWP, where the fourth BWP is a BWP pair including an uplink BWP and adownlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

For the method provided in this embodiment, refer to the methods in FIG.12 to FIG. 15. Details are not described again.

FIG. 17 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.17, the method is specifically as follows:

701. User equipment receives control signaling sent by a network device,where the control signaling is used to trigger the user equipment toperform a random access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

In this embodiment, for this step, refer to step 501 in FIG. 14. Detailsare not described again.

702. The user equipment activates the second BWP.

In this embodiment, for this step, refer to step 502 in FIG. 14. Detailsare not described again.

703. The user equipment sends a random access preamble to the networkdevice on the second BWP.

In this embodiment, for this step, refer to step 503 in FIG. 14. Detailsare not described again.

704. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the RAR message is scheduled by using first DCI, and the BWPidentifier is carried in the first DCI.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 704 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step 704specifically includes receiving, by the user equipment on the uplink BWPof the second BWP, the RAR message sent by the network device.

In an optional implementation, step 704 specifically includes receiving,by the user equipment on a fourth BWP, the RAR message sent by thenetwork device, where the fourth BWP is a BWP pair including an uplinkBWP and a downlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 703, the method further includes step 707: The user equipmentactivates the fourth BWP, and deactivates the second BWP.

705. The user equipment activates the first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is the identifier of the secondBWP, the first BWP corresponding to the BWP is the second BWP, and itmay be determined that the UL grant included in the RAR message is a ULgrant corresponding to the second BWP of the user equipment in the firstserving cell. In this case, the user equipment does not need to performBWP switching, in other words, the first BWP is in an active state, andthe user equipment does not need to further activate the first BWP. Inthis case, the user equipment may send data or signaling to the networkdevice on the second BWP of the first serving cell based on the UL grantin the RAR message.

In a second case, if the BWP identifier is not the identifier of thesecond BWP, the first BWP corresponding to the BWP is different from thesecond BWP, and it may be determined that the UL grant included in theRAR message is a UL grant corresponding to the first BWP of the userequipment in the first serving cell. In this case, the user equipmentneeds to switch to the first BWP, in other words, deactivate the secondBWP, and activate the first BWP. In this case, the user equipment maysend data or signaling to the network device on the first BWP of thefirst serving cell based on the UL grant in the RAR message.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier. Optionally, the firstBWP is an initial active BWP of the user equipment in the first servingcell, or the first BWP is a first active BWP of the user equipment inthe first serving cell, or the first BWP is a default BWP of the userequipment in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is used by the user equipment to perform random access in the firstserving cell, or the first BWP is a BWP configured by the network devicefor the user equipment, and the first BWP is a BWP used by the userequipment to perform contention free random access in the first servingcell, or the first BWP is a BWP activated when the user equipmentperforms random access, or the first BWP is a BWP activated when theuser equipment performs contention free random access.

In addition, in the second case, after the user equipment determinesthat the RAR message is received, the user equipment needs to switch tothe first BWP when determining that an identifier that is of a preambleand that is included in the RAR message is an identifier of the preamblesent by the user equipment.

706. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 506 in FIG. 14. Detailsare not described again.

FIG. 18 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 18, themethod is specifically as follows:

S91. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

S92. The user equipment activates the second BWP.

S93. The user equipment sends a random access preamble to the networkdevice on the second BWP.

S94. The network device sends an RAR message and a BWP identifier to theuser equipment, where the RAR message includes a UL grant, the RARmessage is scheduled by using first DCI, and the BWP identifier iscarried in the first DCI.

S95. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S96. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 701 to 706 in FIG. 17 are implemented in steps 581 to 586.Details are not described again.

In this embodiment, the user equipment receives the RAR message and theBWP identifier that are sent by the network device, where the RARmessage includes the UL grant, the RAR message is scheduled by using thefirst DCI, and the BWP identifier is carried in the first DCI, and theuser equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier. In this way, the user equipment cancomplete a random access procedure based on the BWP identifier indicatedby the network device. The BWP corresponding to the BWP identifier isconsistent with the BWP indicated by the UL grant sent by the networkdevice, so that uplink data can be effectively transmitted by using theUL grant in the RAR message.

FIG. 19 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.19, the method is specifically as follows:

801. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling includes anidentifier of a second BWP.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

802. The network device sends an RAR message and a BWP identifier to theuser equipment, where the RAR message includes a UL grant, the RARmessage is scheduled by using first DCI, and the BWP identifier iscarried in the first DCI.

In an optional implementation, the RAR message includes the UL grant,and the UL grant includes or indicates the BWP identifier.

In an optional implementation, a first BWP is an initial active BWP ofthe user equipment in the first serving cell, or a first BWP is a firstactive BWP of the user equipment in the first serving cell, or a firstBWP is a default BWP of the user equipment in the first serving cell, ora first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or a first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or a first BWP is a BWPactivated when the user equipment performs random access, or a first BWPis a BWP activated when the user equipment performs contention freerandom access.

In an optional implementation, the first BWP and the second BWP areuplink BWPs, and the first BWP and the second BWP may be a same BWP, ormay be different BWPs.

In an optional implementation, step 602 specifically includes sending,by the network device, the RAR message to the user equipment on a thirdBWP, where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In an optional implementation, the first BWP and the second BWP each area BWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step 602specifically includes sending, by the network device, the RAR message tothe user equipment on the uplink BWP of the second BWP.

In an optional implementation, step 602 specifically includes sending,by the network device, the RAR message to the user equipment on a fourthBWP, where the fourth BWP is a BWP pair including an uplink BWP and adownlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

For the method provided in this embodiment, refer to the methods in FIG.17 and FIG. 18. Details are not described again.

FIG. 20 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.20, the method is specifically as follows:

901. User equipment receives control signaling sent by a network device,where the control signaling is used to trigger the user equipment toperform a random access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

In this embodiment, for this step, refer to step 501 in FIG. 14. Detailsare not described again.

902. The user equipment activates the second BWP.

In this embodiment, for this step, refer to step 502 in FIG. 14. Detailsare not described again.

903. The user equipment sends a random access preamble to the networkdevice on the second BWP.

In this embodiment, for this step, refer to step 503 in FIG. 14. Detailsare not described again.

904. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the BWP identifier is carried in second DCI, and the second DCIis DCI for instructing the terminal device to switch a BWP, or thesecond DCI is DCI for instructing the terminal device to switch a pairof an uplink BWP and a downlink BWP.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 904 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step 904specifically includes receiving, by the user equipment on the uplink BWPof the second BWP, the RAR message sent by the network device.

In an optional implementation, step 904 specifically includes receiving,by the user equipment on a fourth BWP, the RAR message sent by thenetwork device, where the fourth BWP is a BWP pair including an uplinkBWP and a downlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 903, the method further includes step 907: The user equipmentactivates the fourth BWP, and deactivates the second BWP.

905. The user equipment activates the first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is the identifier of the secondBWP, the first BWP corresponding to the BWP is the second BWP, and itmay be determined that the UL grant included in the RAR message is a ULgrant corresponding to the second BWP of the user equipment in the firstserving cell. In this case, the user equipment does not need to performBWP switching, in other words, the first BWP is in an active state, andthe user equipment does not need to further activate the first BWP. Inthis case, the user equipment may send data or signaling to the networkdevice on the second BWP of the first serving cell based on the UL grantin the RAR message.

In a second case, if the BWP identifier is not the identifier of thesecond BWP, the first BWP corresponding to the BWP is different from thesecond BWP, and it may be determined that the UL grant included in theRAR message is a UL grant corresponding to the first BWP of the userequipment in the first serving cell. In this case, the user equipmentneeds to switch to the first BWP, in other words, deactivate the secondBWP, and activate the first BWP. In this case, the user equipment maysend data or signaling to the network device on the first BWP of thefirst serving cell based on the UL grant in the RAR message.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier. Optionally, the firstBWP is an initial active BWP of the user equipment in the first servingcell, or the first BWP is a first active BWP of the user equipment inthe first serving cell, or the first BWP is a default BWP of the userequipment in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is used by the user equipment to perform random access in the firstserving cell, or the first BWP is a BWP configured by the network devicefor the user equipment, and the first BWP is a BWP used by the userequipment to perform contention free random access in the first servingcell, or the first BWP is a BWP activated when the user equipmentperforms random access, or the first BWP is a BWP activated when theuser equipment performs contention free random access.

In addition, in the second case, after the user equipment determinesthat the RAR message is received, the user equipment needs to switch tothe first BWP when determining that an identifier that is of a preambleand that is included in the RAR message is an identifier of the preamblesent by the user equipment.

906. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 706 in FIG. 14. Detailsare not described again.

FIG. 21 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 21, themethod is specifically as follows:

S181. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure, and the control signaling includes anidentifier of a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

S182. The user equipment activates the second BWP.

S183. The user equipment sends a random access preamble to the networkdevice on the second BWP.

S184. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

S185. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S186. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 901 to 906 in FIG. 20 are implemented in steps S181 toS86. Details are not described again.

In this embodiment, the user equipment receives the RAR message and theBWP identifier that are sent by the network device, where the RARmessage includes the UL grant, the BWP identifier is carried in thesecond DCI, and the second DCI is DCI for instructing the terminaldevice to switch a BWP, or the second DCI is DCI for instructing theterminal device to switch a pair of an uplink BWP and a downlink BWP,and the user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier. In this way, the user equipment cancomplete a random access procedure based on the BWP identifier indicatedby the network device. The BWP corresponding to the BWP identifier isconsistent with the BWP indicated by the UL grant sent by the networkdevice, so that uplink data can be effectively transmitted by using theUL grant in the RAR message.

FIG. 22 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.22, the method is specifically as follows:

2201. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling includes anidentifier of a second BWP.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

2202. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

In an optional implementation, the RAR message includes the UL grant,and the UL grant includes or indicates the BWP identifier.

In an optional implementation, a first BWP is an initial active BWP ofthe user equipment in the first serving cell, or a first BWP is a firstactive BWP of the user equipment in the first serving cell, or a firstBWP is a default BWP of the user equipment in the first serving cell, ora first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or a first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or a first BWP is a BWPactivated when the user equipment performs random access, or a first BWPis a BWP activated when the user equipment performs contention freerandom access.

In an optional implementation, the first BWP and the second BWP areuplink BWPs, and the first BWP and the second BWP may be a same BWP, ormay be different BWPs.

In an optional implementation, step 2202 specifically includes sending,by the network device, the RAR message to the user equipment on a thirdBWP, where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In an optional implementation, the first BWP and the second BWP each area BWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step 602specifically includes sending, by the network device, the RAR message tothe user equipment on the uplink BWP of the second BWP.

In an optional implementation, step 2202 specifically includes sending,by the network device, the RAR message to the user equipment on a fourthBWP, where the fourth BWP is a BWP pair including an uplink BWP and adownlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

For the method provided in this embodiment, refer to the methods in FIG.20 and FIG. 21. Details are not described again.

FIG. 23 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.23, the method is specifically as follows:

2301. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, at least one serving cell is configured for the userequipment, and the at least one serving cell includes a first servingcell. The user equipment receives, in the first serving cell, thecontrol signaling sent by the network device.

In this embodiment, the network device configures an initial activesecond BWP for the user equipment in the first serving cell, andconfigures a PRACH resource only for the initial active second BWP. Theinitial active second BWP may be configured by the network device orselected by the user equipment. In this case, the user equipmentoperates in the first serving cell. In other words, the user equipmentcommunicates with the network device in the first serving cell.Optionally, the user equipment operates in a secondary serving cell, andthe secondary serving cell and a primary serving cell of the userequipment belong to different TAGs, or the user equipment operates in aprimary serving cell.

The network device sends the control signaling to the user equipment.The control signaling may be signaling or a signal, and the controlsignaling is used to trigger the user equipment to perform a randomaccess procedure. Further, the control signaling is a PDCCH order. Inthis case, the user equipment has an initial active downlink BWP in thefirst serving cell, and the user equipment may receive the PDCCH orderon the downlink BWP of the first serving cell. Alternatively, the userequipment may receive the PDCCH order on an initial active downlink BWPof a second serving cell used to schedule the first serving cell. Inthis case, the PDCCH order includes a cell index of the current servingcell.

In this step, the control signaling does not carry a BWP identifier orindicate a BWP identifier.

2302. The user equipment sends a random access preamble to the networkdevice on the initial active second BWP.

In this embodiment, because the user equipment has an initial activesecond BWP, and a PRACH resource is configured only for the initialactive second BWP, the user equipment directly sends the random accesspreamble to the network device on the initial active second BWP. Forexample, when the user equipment communicates with the network device ina secondary serving cell, the initial active second BWP is a BWPactivated when the user equipment activates the secondary serving cell.

2303. The user equipment receives an RAR message sent by the networkdevice, where the RAR message includes a UL grant, and the UL grantincludes or indicates a BWP identifier.

In this embodiment, the network device sends the RAR message to the userequipment. The RAR message includes the UL grant, and the RAR messageincludes the BWP identifier, or the RAR message indicates the BWPidentifier. Specifically, the UL grant in the RAR message includes theBWP identifier, or the UL grant in the RAR message indicates the BWPidentifier. Alternatively, the BWP identifier is directly included inthe RAR message as an information field in the RAR message.

In an optional implementation, there are the following implementationsof step 2303:

In a first implementation of step 2303, a first BWP and the second BWPare uplink BWPs, and the first BWP and the second BWP may be a same BWP,or may be different BWPs. Step 2303 specifically includes receiving, bythe user equipment on a third BWP, the RAR message sent by the networkdevice, where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In this embodiment, the first BWP is an uplink BWP, and the second BWPis also an uplink BWP. In this case, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 2303, the userequipment receives, on the third BWP, the RAR message sent by thenetwork device, where the third BWP is a downlink BWP.

In a second implementation of step 2303, a first BWP and the second BWPeach are a BWP pair including an uplink BWP and a downlink BWP, and thefirst BWP and the second BWP may be a same BWP, or may be differentBWPs. Step 2303 specifically includes receiving, by the user equipmenton the uplink BWP of the second BWP, the RAR message sent by the networkdevice.

In this embodiment, the first BWP is a BWP pair including an uplink BWPand a downlink BWP, and the second BWP is a BWP pair including an uplinkBWP and a downlink BWP. In addition, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 2303, the userequipment receives, on the uplink BWP of the second BWP, the RAR messagesent by the network device.

In a third implementation of step 2303, the user equipment receives, ona fourth BWP, the RAR message sent by the network device, where thefourth BWP is a BWP pair including an uplink BWP and a downlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 503, the method further includes step 507: The user equipmentactivates the fourth BWP, and deactivates the second BWP.

In this embodiment, the fourth BWP is provided. Optionally, the fourthBWP is a BWP pair including an uplink BWP and a downlink BWP. The userequipment first needs to switch to the fourth BWP, in other words, theuser equipment activates the fourth BWP, and deactivates the second BWP.Then the user equipment may receive, on the fourth BWP, the RAR messagesent by the network device.

2304. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is an identifier of the initialactive second BWP, the first BWP corresponding to the BWP is the secondBWP, and it may be determined that the UL grant included in the RARmessage is a UL grant corresponding to the second BWP of the userequipment in the first serving cell. In this case, the user equipmentdoes not need to perform BWP switching, in other words, the first BWP isin an active state, and the user equipment does not need to furtheractivate the first BWP. In this case, the user equipment may send dataor signaling to the network device on the second BWP of the firstserving cell based on the UL grant in the RAR message.

In a second case, if the BWP identifier is not an identifier of theinitial active second BWP, the first BWP corresponding to the BWP isdifferent from the second BWP, and it may be determined that the ULgrant included in the RAR message is a UL grant corresponding to thefirst BWP of the user equipment in the first serving cell. In this case,the user equipment needs to switch to the first BWP, in other words,deactivate the second BWP, and activate the first BWP. In this case, theuser equipment may send data or signaling to the network device on thefirst BWP of the first serving cell based on the UL grant in the RARmessage.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier.

2305. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, the user equipment sends, on the first BWP indicatedby the network device, data or an instruction to the network device byusing the physical resource indicated by the UL grant in the RARmessage.

FIG. 24 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 24, themethod is specifically as follows:

S2401. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S2402. The user equipment sends a random access preamble to the networkdevice on an initial active second BWP.

S2403. The network device sends an RAR message to the user equipment,where the RAR message includes a UL grant, and the UL grant includes orindicates a BWP identifier.

S2404. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in a first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S2405. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 2301 to 2305 in FIG. 23 are implemented in steps S2401 toS2405. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the initial active second BWP, theuser equipment receives the RAR message sent by the network device,where the RAR message includes or indicates the BWP identifier, and theuser equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier. In this way, the user equipment canperform uplink transmission on the first BWP indicated by the networkdevice. The first BWP corresponding to the BWP identifier is consistentwith the BWP indicated by the UL grant sent by the network device, sothat uplink data can be effectively transmitted by using the UL grant inthe RAR message.

FIG. 25 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.25, the method is specifically as follows:

2501. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

2502. The network device receives a random access preamble sent by theuser equipment on an initial active second BWP.

2503. The network device sends an RAR message to the user equipment,where the RAR message includes a UL grant, and the UL grant includes orindicates a BWP identifier.

For the method provided in this embodiment, refer to the methods in FIG.23 and FIG. 24. Details are not described again.

FIG. 26 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.26, the method is specifically as follows:

2601. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, for this step, refer to step 2301 in FIG. 23.Details are not described again.

2602. The user equipment sends a random access preamble to the networkdevice on an initial active second BWP.

In this embodiment, for this step, refer to step 2302 in FIG. 23.Details are not described again.

2603. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the RAR message is scheduled by using first DCI, and the BWPidentifier is carried in the first DCI.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 2603 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thethird BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step2603 specifically includes receiving, by the user equipment on theuplink BWP of the second BWP, the RAR message sent by the networkdevice.

In an optional implementation, step 704 specifically includes receiving,by the user equipment on a fourth BWP, the RAR message sent by thenetwork device, where the fourth BWP is a BWP pair including an uplinkBWP and a downlink BWP.

The fourth BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thefourth BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 2602, the method further includes step 2606: The userequipment activates the fourth BWP, and deactivates the second BWP.

2604. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, for this step, refer to step 2304 in FIG. 23. Detailsare not described again.

2605. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 2305 in FIG. 23.Details are not described again.

FIG. 27 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 27, themethod is specifically as follows:

S2701. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S2702. The user equipment sends a random access preamble to the networkdevice on an initial active second BWP.

S2703. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the RARmessage is scheduled by using first DCI, and the BWP identifier iscarried in the first DCI.

S2704. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in a first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S2705. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 2601 to 2605 in FIG. 26 are implemented in steps S2701 toS2705. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the initial active second BWP, theuser equipment receives the RAR message and the BWP identifier that aresent by the network device, where the RAR message includes the UL grant,the RAR message is scheduled by using the first DCI, and the BWPidentifier is carried in the first DCI, and the user equipment performsuplink transmission on the first BWP corresponding to the BWPidentifier. In this way, the user equipment can perform uplinktransmission on the first BWP indicated by the network device. The firstBWP corresponding to the BWP identifier is consistent with the BWPindicated by the UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in the RARmessage.

FIG. 28 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.28, the method is specifically as follows:

2801. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

2802. The network device receives a random access preamble sent by theuser equipment on an initial active second BWP.

2803. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the RARmessage is scheduled by using first DCI, and the BWP identifier iscarried in the first DCI.

For the method provided in this embodiment, refer to the methods in FIG.26 and FIG. 27. Details are not described again.

FIG. 29 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.29, the method is specifically as follows:

2901. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, for this step, refer to step 2301 in FIG. 23.Details are not described again.

2902. The user equipment sends a random access preamble to the networkdevice on an initial active second BWP.

In this embodiment, for this step, refer to step 2302 in FIG. 23.Details are not described again.

2903. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the BWP identifier is carried in second DCI, and the second DCIis DCI for instructing the terminal device to switch a BWP, or thesecond DCI is DCI for instructing the terminal device to switch a pairof an uplink BWP and a downlink BWP.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 2903 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thethird BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step2903 specifically includes receiving, by the user equipment on theuplink BWP of the second BWP, the RAR message sent by the networkdevice.

In an optional implementation, step 704 specifically includes receiving,by the user equipment on a fourth BWP, the RAR message sent by thenetwork device, where the fourth BWP is a BWP pair including an uplinkBWP and a downlink BWP.

The fourth BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thefourth BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 292, the method further includes step 2906: The userequipment activates the fourth BWP, and deactivates the second BWP.

2904. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, for this step, refer to step 2304 in FIG. 23. Detailsare not described again.

2905. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 2305 in FIG. 23.Details are not described again.

FIG. 30 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 30, themethod is specifically as follows:

S3001. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S3002. The user equipment sends a random access preamble to the networkdevice on an initial active second BWP.

S3003. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

S3004. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell.

S3005. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 2901 to 2905 in FIG. 29 are implemented in steps S3001 toS3005. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the initial active second BWP, theuser equipment receives the RAR message and the BWP identifier that aresent by the network device, where the RAR message includes the UL grant,and the BWP identifier is carried in the second DCI, the user equipmentreceives the RAR message and the BWP identifier that are sent by thenetwork device, and the user equipment performs uplink transmission onthe first BWP corresponding to the BWP identifier. In this way, the userequipment can perform uplink transmission on the first BWP indicated bythe network device. The first BWP corresponding to the BWP identifier isconsistent with the BWP indicated by the UL grant sent by the networkdevice, so that uplink data can be effectively transmitted by using theUL grant in the RAR message.

FIG. 31 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.31, the method is specifically as follows:

3101. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

3102. The network device receives a random access preamble sent by theuser equipment on an initial active second BWP.

3103. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

For the method provided in this embodiment, refer to the methods in FIG.29 and FIG. 30. Details are not described again.

FIG. 32 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.32, the method is specifically as follows:

3201. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, at least one serving cell is configured for the userequipment, and the at least one serving cell includes a first servingcell. The user equipment receives, in the first serving cell, thecontrol signaling sent by the network device.

In this embodiment, the network device configures a default second BWPfor the user equipment in the first serving cell, and configures a PRACHresource only for the default second BWP. The default second BWP may beconfigured by the network device or selected by the user equipment. Inthis case, the user equipment operates in the first serving cell. Inother words, the user equipment communicates with the network device inthe first serving cell. Optionally, the user equipment operates in asecondary serving cell, and the secondary serving cell and a primaryserving cell of the user equipment belong to different TAGs, or the userequipment operates in a primary serving cell.

The network device sends the control signaling to the user equipment.The control signaling may be signaling or a signal, and the controlsignaling is used to trigger the user equipment to perform a randomaccess procedure. Further, the control signaling is a PDCCH order. Inthis case, the user equipment has a default downlink BWP in the firstserving cell, and the user equipment may receive the PDCCH order on thedownlink BWP of the first serving cell. Alternatively, the userequipment may receive the PDCCH order on a default downlink BWP of asecond serving cell used to schedule the first serving cell. In thiscase, the PDCCH order includes a cell index of the current serving cell.

In this step, the control signaling does not carry a BWP identifier orindicate a BWP identifier.

3202. The user equipment sends a random access preamble to the networkdevice on the default second BWP.

In this embodiment, because the user equipment has a default second BWP,and a PRACH resource is configured only for the default second BWP, theuser equipment directly sends the random access preamble to the networkdevice on the default second BWP. For example, when the user equipmentcommunicates with the network device in a secondary serving cell, thedefault second BWP is a BWP activated when the user equipment activatesthe secondary serving cell.

3203. The user equipment receives an RAR message sent by the networkdevice, where the RAR message includes a UL grant, and the UL grantincludes or indicates a BWP identifier.

In this embodiment, the network device sends the RAR message to the userequipment. The RAR message includes the UL grant, and the RAR messageincludes the BWP identifier, or the RAR message indicates the BWPidentifier. Specifically, the UL grant in the RAR message includes theBWP identifier, or the UL grant in the RAR message indicates the BWPidentifier. Alternatively, the BWP identifier is directly included inthe RAR message as an information field in the RAR message.

In an optional implementation, there are the following implementationsof step 3203:

In a first implementation of step 3203, a first BWP and the second BWPare uplink BWPs, and the first BWP and the second BWP may be a same BWP,or may be different BWPs. Step 3203 specifically includes receiving, bythe user equipment on a third BWP, the RAR message sent by the networkdevice, where the third BWP is a downlink BWP.

The third BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe third BWP is a BWP used when the user equipment receives the controlsignaling in the first serving cell.

In this embodiment, the first BWP is an uplink BWP, and the second BWPis also an uplink BWP. In this case, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 3203, the userequipment receives, on the third BWP, the RAR message sent by thenetwork device, where the third BWP is a downlink BWP.

In a second implementation of step 3203, a first BWP and the second BWPeach are a BWP pair including an uplink BWP and a downlink BWP, and thefirst BWP and the second BWP may be a same BWP, or may be differentBWPs. Step 3203 specifically includes receiving, by the user equipmenton the uplink BWP of the second BWP, the RAR message sent by the networkdevice.

In this embodiment, the first BWP is a BWP pair including an uplink BWPand a downlink BWP, and the second BWP is a BWP pair including an uplinkBWP and a downlink BWP. In addition, the first BWP and the second BWPmay be a same BWP, or may be different BWPs. In step 3203, the userequipment receives, on the uplink BWP of the second BWP, the RAR messagesent by the network device.

In a third implementation of step 3203, the user equipment receives, ona fourth BWP, the RAR message sent by the network device, where thefourth BWP is a BWP pair including an uplink BWP and a downlink BWP.

The fourth BWP is an active BWP in the second serving cell when the userequipment receives the control signaling in the first serving cell, orthe fourth BWP is a BWP used when the user equipment receives thecontrol signaling in the first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 503, the method further includes step 507: The user equipmentactivates the fourth BWP, and deactivates the second BWP.

In this embodiment, the fourth BWP is provided. Optionally, the fourthBWP is a BWP pair including an uplink BWP and a downlink BWP. The userequipment first needs to switch to the fourth BWP, in other words, theuser equipment activates the fourth BWP, and deactivates the second BWP.Then the user equipment may receive, on the fourth BWP, the RAR messagesent by the network device.

3204. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in the first serving cell, or the first BWP is a firstactive BWP of the user equipment in the first serving cell, or the firstBWP is a default BWP of the user equipment in the first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is an identifier of the defaultsecond BWP, the first BWP corresponding to the BWP is the second BWP,and it may be determined that the UL grant included in the RAR messageis a UL grant corresponding to the second BWP of the user equipment inthe first serving cell. In this case, the user equipment does not needto perform BWP switching, in other words, the first BWP is in an activestate, and the user equipment does not need to further activate thefirst BWP. In this case, the user equipment may send data or signalingto the network device on the second BWP of the first serving cell basedon the UL grant in the RAR message.

In a second case, if the BWP identifier is not an identifier of thedefault second BWP, the first BWP corresponding to the BWP is differentfrom the second BWP, and it may be determined that the UL grant includedin the RAR message is a UL grant corresponding to the first BWP of theuser equipment in the first serving cell. In this case, the userequipment needs to switch to the first BWP, in other words, deactivatethe second BWP, and activate the first BWP. In this case, the userequipment may send data or signaling to the network device on the firstBWP of the first serving cell based on the UL grant in the RAR message.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier.

3205. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, the user equipment sends, on the first BWP indicatedby the network device, data or an instruction to the network device byusing the physical resource indicated by the UL grant in the RARmessage.

FIG. 33 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 33, themethod is specifically as follows:

S3301. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S3302. The user equipment sends a random access preamble to the networkdevice on a default second BWP.

S3303. The network device sends an RAR message to the user equipment,where the RAR message includes a UL grant, and the UL grant includes orindicates a BWP identifier.

S3304. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in a first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S3305. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 3201 to 3205 in FIG. 32 are implemented in steps S3301 toS3305. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the default second BWP, the userequipment receives the RAR message sent by the network device, where theRAR message includes or indicates the BWP identifier, and the userequipment performs uplink transmission on the first BWP corresponding tothe BWP identifier. In this way, the user equipment can perform uplinktransmission on the first BWP indicated by the network device. The firstBWP corresponding to the BWP identifier is consistent with the BWPindicated by the UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in the RARmessage.

FIG. 34 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.34, the method is specifically as follows:

3401. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

3402. The network device receives a random access preamble sent by theuser equipment on a default second BWP.

3403. The network device sends an RAR message to the user equipment,where the RAR message includes a UL grant, and the UL grant includes orindicates a BWP identifier.

For the method provided in this embodiment, refer to the methods in FIG.32 and FIG. 33. Details are not described again.

FIG. 35 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.35, the method is specifically as follows:

3501. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, for this step, refer to step 3201 in FIG. 32.Details are not described again.

3502. The user equipment sends a random access preamble to the networkdevice on a default second BWP.

In this embodiment, for this step, refer to step 3202 in FIG. 32.Details are not described again.

3503. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the RAR message is scheduled by using first DCI, and the BWPidentifier is carried in the first DCI.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 3503 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thethird BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step3503 specifically includes receiving, by the user equipment on theuplink BWP of the second BWP, the RAR message sent by the networkdevice.

In an optional implementation, step 3503 specifically includesreceiving, by the user equipment on a fourth BWP, the RAR message sentby the network device, where the fourth BWP is a BWP pair including anuplink BWP and a downlink BWP.

The fourth BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thefourth BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 3502, the method further includes step 3506: The userequipment activates the fourth BWP, and deactivates the second BWP.

3504. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in the first serving cell, or the first BWP is a firstactive BWP of the user equipment in the first serving cell, or the firstBWP is a default BWP of the user equipment in the first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, for this step, refer to step 3204 in FIG. 32.Details are not described again.

3505. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 3205 in FIG. 32.Details are not described again.

FIG. 36 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 36, themethod is specifically as follows:

S3601. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S3602. The user equipment sends a random access preamble to the networkdevice on a default second BWP.

S3603. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the RAR message is scheduled by using first DCI, and the BWPidentifier is carried in the first DCI.

S3604. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in a first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S3605. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 3501 to 3505 in FIG. 35 are implemented in steps S3601 toS3605. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the default second BWP, the userequipment receives the RAR message and the BWP identifier that are sentby the network device, where the RAR message includes the UL grant, theRAR message is scheduled by using the first DCI, and the BWP identifieris carried in the first DCI, and the user equipment performs uplinktransmission on the first BWP corresponding to the BWP identifier. Inthis way, the user equipment can perform uplink transmission on thefirst BWP indicated by the network device. The first BWP correspondingto the BWP identifier is consistent with the BWP indicated by the ULgrant sent by the network device, so that uplink data can be effectivelytransmitted by using the UL grant in the RAR message.

FIG. 37 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.37, the method is specifically as follows:

3701. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

3702. The network device receives a random access preamble sent by theuser equipment on a default second BWP.

3703. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the RARmessage is scheduled by using first DCI, and the BWP identifier iscarried in the first DCI.

For the method provided in this embodiment, refer to the methods in FIG.35 and FIG. 36. Details are not described again.

FIG. 38 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.38, the method is specifically as follows:

3801. User equipment receives control signaling sent by a networkdevice, where the control signaling is used to trigger the userequipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In this embodiment, for this step, refer to step 3201 in FIG. 32.Details are not described again.

3802. The user equipment sends a random access preamble to the networkdevice on a default second BWP.

In this embodiment, for this step, refer to step 3202 in FIG. 32.Details are not described again.

3803. The user equipment receives an RAR message and a BWP identifierthat are sent by the network device, where the RAR message includes a ULgrant, the BWP identifier is carried in second DCI, and the second DCIis DCI for instructing the terminal device to switch a BWP, or thesecond DCI is DCI for instructing the terminal device to switch a pairof an uplink BWP and a downlink BWP.

In an optional implementation, a first BWP and the second BWP are uplinkBWPs, and the first BWP and the second BWP may be a same BWP, or may bedifferent BWPs. Step 3803 specifically includes receiving, by the userequipment on a third BWP, the RAR message sent by the network device,where the third BWP is a downlink BWP.

The third BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thethird BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, a first BWP and the second BWP each are aBWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Step3803 specifically includes receiving, by the user equipment on theuplink BWP of the second BWP, the RAR message sent by the networkdevice.

In an optional implementation, step 3803 specifically includesreceiving, by the user equipment on a fourth BWP, the RAR message sentby the network device, where the fourth BWP is a BWP pair including anuplink BWP and a downlink BWP.

The fourth BWP is an active BWP in a second serving cell when the userequipment receives the control signaling in a first serving cell, or thefourth BWP is a BWP used when the user equipment receives the controlsignaling in a first serving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,after step 3802, the method further includes step 3806: The userequipment activates the fourth BWP, and deactivates the second BWP.

3804. The user equipment activates the first BWP corresponding to theBWP identifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in the first serving cell, or the first BWP is a firstactive BWP of the user equipment in the first serving cell, or the firstBWP is a default BWP of the user equipment in the first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in the first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In this embodiment, for this step, refer to step 3204 in FIG. 32.Details are not described again.

3805. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

In this embodiment, for this step, refer to step 3205 in FIG. 32.Details are not described again.

FIG. 39 is a signaling diagram of another random access method accordingto an embodiment of the present invention. As shown in FIG. 39, themethod is specifically as follows:

S3901. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

S3902. The user equipment sends a random access preamble to the networkdevice on a default second BWP.

S3903. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

S3904. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is a default BWP of theuser equipment in a first serving cell, or the first BWP is a firstactive BWP of the user equipment in a first serving cell, or the firstBWP is a default BWP of the user equipment in a first serving cell, orthe first BWP is a BWP configured by the network device for the userequipment, and the first BWP is used by the user equipment to performrandom access in a first serving cell, or the first BWP is a BWPconfigured by the network device for the user equipment, and the firstBWP is a BWP used by the user equipment to perform contention freerandom access in a first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

S3905. The user equipment performs uplink transmission on the first BWPcorresponding to the BWP identifier, where a physical resource used forthe uplink transmission is a physical resource indicated by the ULgrant.

Herein, steps 3801 to 3805 in FIG. 38 are implemented in steps S3901 toS3905. Details are not described again.

In this embodiment, the user equipment receives the control signalingsent by the network device, the user equipment sends the random accesspreamble to the network device on the default second BWP, the userequipment receives the RAR message and the BWP identifier that are sentby the network device, where the RAR message includes the UL grant, andthe BWP identifier is carried in the second DCI, and the user equipmentperforms uplink transmission on the first BWP corresponding to the BWPidentifier. In this way, the user equipment can perform uplinktransmission on the first BWP indicated by the network device. The firstBWP corresponding to the BWP identifier is consistent with the BWPindicated by the UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in the RARmessage.

FIG. 40 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.40, the method is specifically as follows:

4001. A network device sends control signaling to user equipment, wherethe control signaling is used to trigger the user equipment to perform arandom access procedure.

In an optional implementation, the control signaling is a PDCCH order.

4002. The network device receives a random access preamble sent by theuser equipment on a default second BWP.

4003. The network device sends an RAR message and a BWP identifier tothe user equipment, where the RAR message includes a UL grant, the BWPidentifier is carried in second DCI, and the second DCI is DCI forinstructing the terminal device to switch a BWP, or the second DCI isDCI for instructing the terminal device to switch a pair of an uplinkBWP and a downlink BWP.

For the method provided in this embodiment, refer to the methods in FIG.38 and FIG. 39. Details are not described again.

Based on the contention free random access procedure in FIG. 4 or FIG.5, in the scenario shown in FIG. 1b , the solutions of the embodimentsof this application are as follows: The method provided below is notonly applicable to a case in which user equipment is handed over from asource network device to a target network device, but also applicable toa case in which a network device configures dual connectivity for userequipment. For the case in which the user equipment is handed over fromthe source network device to the target network device, a first messagein the following method may be, for example, a handover request message,and a second message may be, for example, a handover requestacknowledgment message. For the case in which the network deviceconfigures dual connectivity for the user equipment, a first message inthe following method may be, for example, a secondary node additionrequest message, and a second message may be, for example, a secondarynode addition request acknowledgment message.

FIG. 41 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.41, the method is specifically as follows:

4101. User equipment receives an RRC connection reconfiguration messagesent by a first network device, where the RRC connection reconfigurationmessage is included in a first message sent by a second network deviceto the first network device, and the RRC connection reconfigurationmessage is used to indicate the primary serving cell under the secondnetwork device for the user equipment, and indicate an active BWP in theprimary serving cell.

In an optional implementation, the first message is a response messagesent by the second network device after the second network devicereceives a second message sent by the first network device, and thesecond message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by the userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

In this embodiment, the network device configures at least one BWP forthe user equipment in the secondary serving cell, and a PRACH resourceis configured for each of the at least one BWP.

The first network device sends the second message to the second networkdevice. The second message includes at least one of the followinginformation: (1) the information about the uplink BWP or the BWP pairactivated by the user equipment, (2) the information about all theuplink BWPs or the BWP pairs configured for the user equipment, (3)information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, (4) information about a logical channel of the userequipment, where the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, and (5) informationabout a logical channel of the user equipment, where the logical channelis all logical channels of the user equipment.

Then the second network device sends the first message to the firstnetwork device. The first message includes the RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates the primary serving cell used by the user equipment in thesecond network device, and the RRC connection reconfiguration messageindicates the active BWP of the user equipment in the primary servingcell.

The first network device sends the RRC connection reconfigurationmessage to the user equipment.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

4102. The user equipment initiates a random access procedure on theactive BWP.

In an optional implementation, there are the following implementationsof step 4102:

In a first implementation of step 4102, the active BWP includes anuplink BWP and a downlink BWP, and step 4102 specifically includes thefollowing steps:

41021 a. The user equipment sends a random access preamble to the secondnetwork device on the uplink BWP in the active BWP.

41022 a. The user equipment receives, on the downlink BWP in the activeBWP, an RAR message sent by the second network device, where the RARmessage includes a UL grant.

41023 a. The user equipment performs uplink transmission on the uplinkBWP in the active BWP, where a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In this embodiment, the active BWP includes the uplink BWP and thedownlink BWP. The user equipment may send the preamble to the secondnetwork device on the uplink BWP in the active BWP. Then the secondnetwork device sends the RAR message to the user equipment, where theRAR message includes the UL grant, and the UL grant is a UL grantcorresponding to the uplink BWP in the active BWP. The user equipmentreceives the RAR message on the downlink BWP in the active BWP. Then theuser equipment sends data or signaling to the second network device onthe uplink BWP in the active BWP by using the physical resourceindicated by the UL grant in the RAR message.

In a second implementation of step 4102, the active BWP is a BWP pairincluding an uplink BWP and a downlink BWP, step 4102 specificallyincludes the following steps:

4102 b. The user equipment sends a random access preamble to the secondnetwork device on the uplink BWP of the BWP pair.

4102 b. The user equipment receives, on the downlink BWP of the BWPpair, an RAR message sent by the second network device, where the RARmessage includes a UL grant.

4102 b. The user equipment performs uplink transmission on the uplinkBWP of the BWP pair, where a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In this embodiment, the active BWP is the BWP pair including an uplinkBWP and a downlink BWP. The user equipment may send the preamble to thesecond network device on the uplink BWP of the BWP pair. Then the secondnetwork device sends the RAR message to the user equipment, where theRAR message includes the UL grant, and the UL grant is a UL grantcorresponding to the uplink BWP of the BWP pair. The user equipmentreceives the RAR message on the downlink BWP of the BWP pair. Then theuser equipment sends data or signaling to the second network device onthe uplink BWP of the BWP pair by using the physical resource indicatedby the UL grant in the RAR message.

FIG. 42 is a signaling diagram 1 of another random access methodaccording to an embodiment of the present invention. As shown in FIG.42, the method is specifically as follows:

S4201. A first network device sends a second message to a second networkdevice.

In an optional implementation, the second message includes at least oneof the following information: (1) information about an uplink BWP or aBWP pair activated by user equipment, (2) information about all uplinkBWPs or BWP pairs configured for the user equipment, (3) informationabout a logical channel of the user equipment, where the logical channelis a logical channel with a highest priority in all logical channels ofthe user equipment that have to-be-transmitted uplink data, (4)information about a logical channel of the user equipment, where thelogical channel is all logical channels of the user equipment that haveto-be-transmitted uplink data, and (5) information about a logicalchannel of the user equipment, where the logical channel is all logicalchannels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

S4202. The second network device sends a first message to the firstnetwork device, where the first message includes an RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates a primary serving cell used by the user equipment in thesecond network device, the RRC connection reconfiguration messageindicates an active BWP of the user equipment in the primary servingcell, and the active BWP includes an uplink BWP and a downlink BWP.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

S4203. The first network device sends the RRC connection reconfigurationmessage to the user equipment.

S4204. The user equipment sends a random access preamble to the secondnetwork device on the uplink BWP in the active BWP.

S4205. The user equipment receives, on the downlink BWP in the activeBWP, an RAR message sent by the second network device, where the RARmessage includes a UL grant.

S4206. The user equipment performs uplink transmission on the uplink BWPin the active BWP, where a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

Herein, steps S4201 to S4206 are step 4101 and a first implementation ofstep 4102 in FIG. 41. Details are not described again.

FIG. 43 is a signaling diagram 2 of another random access methodaccording to an embodiment of the present invention. As shown in FIG.43, the method is specifically as follows:

S4301. A first network device sends a second message to a second networkdevice.

In an optional implementation, the second message includes at least oneof the following information: (1) information about an uplink BWP or aBWP pair activated by user equipment, (2) information about all uplinkBWPs or BWP pairs configured for the user equipment, (3) informationabout a logical channel of the user equipment, where the logical channelis a logical channel with a highest priority in all logical channels ofthe user equipment that have to-be-transmitted uplink data, (4)information about a logical channel of the user equipment, where thelogical channel is all logical channels of the user equipment that haveto-be-transmitted uplink data, and (5) information about a logicalchannel of the user equipment, where the logical channel is all logicalchannels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

S4302. The second network device sends a first message to the firstnetwork device, where the first message includes an RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates a primary serving cell used by the user equipment in thesecond network device, the RRC connection reconfiguration messageindicates an active BWP of the user equipment in the primary servingcell, and the active BWP is a BWP pair including an uplink BWP and adownlink BWP.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

S4303. The first network device sends the RRC connection reconfigurationmessage to the user equipment.

S4304. The user equipment sends a random access preamble to the secondnetwork device on the uplink BWP of the BWP pair.

S4305. The user equipment receives, on the downlink BWP of the BWP pair,an RAR message sent by the second network device, where the RAR messageincludes a UL grant.

S4306. The user equipment performs uplink transmission on the uplink BWPof the BWP pair, where a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

Herein, steps S4301 to S4306 are step 4101 and a second implementationof step 4102 in FIG. 41. Details are not described again.

In this embodiment, the user equipment receives the RRC connectionreconfiguration message sent by the first network device, where the RRCconnection reconfiguration message is used to indicate the primaryserving cell of the user equipment in the second network device and theactive BWP in the primary serving cell, and the user equipment initiatesa random access procedure on the active BWP. In this way, the userequipment can complete the random access procedure based on the activeBWP indicated by the network device. The active BWP is consistent with aBWP indicated by the UL grant sent by the network device, so that uplinkdata can be effectively transmitted by using the UL grant in the RARmessage.

FIG. 44 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.44, the method is specifically as follows:

4401. A first network device sends a second message to a second networkdevice.

The second message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

4402. The first network device receives a first message sent by thesecond network device, where the first message includes an RRCconnection reconfiguration message.

In an optional implementation, an active BWP is a BWP in commonconfiguration information of a primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is an active BWP.

In an optional implementation, the active BWP includes an uplink BWP anda downlink BWP.

4403. The first network device sends the RRC connection reconfigurationmessage to the user equipment, where the RRC connection reconfigurationmessage is used to indicate the primary serving cell that is of the userequipment and that is provided by the second network device and theactive BWP in the primary serving cell.

In an optional implementation, the active BWP is a BWP pair including anuplink BWP and a downlink BWP.

For the method provided in this embodiment, refer to the methods in FIG.41 to FIG. 43. Details are not described again.

FIG. 45 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.45, the method is specifically as follows:

4501. User equipment receives an RRC connection reconfiguration messagesent by a first network device, where the RRC connection reconfigurationmessage is included in a first message sent by a second network deviceto the first network device, and the RRC connection reconfigurationmessage is used to indicate the primary serving cell under the secondnetwork device for the user equipment, and indicate an active BWP in theprimary serving cell.

In an optional implementation, the first message is a response messagesent by the second network device after the second network devicereceives a second message sent by the first network device, and thesecond message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by the userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

In this embodiment, the network device configures at least one BWP forthe user equipment in the secondary serving cell, but configures a PRACHresource for only one of the at least one BWP. The BWP for which a PRACHresource is configured is an initial active BWP or a default BWP.

The first network device sends the second message to the second networkdevice. The second message includes at least one of the followinginformation: (1) the information about the uplink BWP or the BWP pairactivated by the user equipment, (2) the information about all theuplink BWPs or the BWP pairs configured for the user equipment, (3)information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, (4) information about a logical channel of the userequipment, where the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, and (5) informationabout a logical channel of the user equipment, where the logical channelis all logical channels of the user equipment.

Then the second network device sends the first message to the firstnetwork device. The first message includes the RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates the primary serving cell used by the user equipment in thesecond network device, and the RRC connection reconfiguration messageindicates the active BWP of the user equipment in the primary servingcell.

The first network device sends the RRC connection reconfigurationmessage to the user equipment.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

4502. The user equipment sends a random access preamble to the secondnetwork device on the active BWP.

In this embodiment, the user equipment sends the preamble to the secondnetwork device on the active BWP.

4503. The user equipment receives, on the active BWP, an RAR messagesent by the second network device, where the RAR message includes orindicates the first BWP identifier.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In this embodiment, the second network device sends the RAR message tothe user equipment. The RAR message includes the first BWP identifier,or the RAR message indicates the first BWP identifier. The userequipment receives the RAR message on the active BWP.

4504. The user equipment activates a first BWP corresponding to the BWPidentifier.

In an optional implementation, the first BWP is an uplink BWP, theactive BWP includes an uplink BWP and a downlink BWP, and the first BWPand the uplink BWP in the active BWP may be a same BWP, or may bedifferent BWPs, or the first BWP is a BWP pair including an uplink BWPand a downlink BWP, the active BWP is a BWP pair including an uplink BWPand a downlink BWP, and the first BWP and the active BWP may be a sameBWP, or may be different BWPs.

In this embodiment, there are three cases as to whether the userequipment needs to activate the BWP corresponding to the BWP identifier.

In a first case, when the user equipment receives a PDCCH order, if theuser equipment has no active BWP in a current serving cell, the userequipment needs to activate the BWP corresponding to the BWP identifier.

In a second case, when the user equipment receives a PDCCH order, if anactive uplink BWP of the user equipment in a current first serving cellis another BWP, the user equipment switches to the BWP corresponding tothe BWP identifier, in other words, the user equipment deactivates theanother BWP, and activates the BWP corresponding to the BWP identifier.

In a third case, when the user equipment receives a PDCCH order, if anactive uplink BWP of the user equipment in a current first serving cellis the BWP corresponding to the BWP identifier, the user equipment doesnot need to perform BWP switching.

In this step, in the first case or the second case, the user equipmentneeds to activate the BWP corresponding to the BWP identifier.

4505. The user equipment performs uplink transmission on the first BWPcorresponding to the first BWP identifier.

In an optional implementation, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In this step, the user equipment sends data or signaling to the networkdevice on the first BWP by using the physical resource indicated by theUL grant in the RAR message.

FIG. 46 is signaling of another random access method according to anembodiment of the present invention. As shown in FIG. 46, the method isspecifically as follows:

S4601. A first network device sends a second message to a second networkdevice, where the second message includes at least one of the followinginformation: (1) information about an uplink BWP or a BWP pair activatedby user equipment, (2) information about all uplink BWPs or BWP pairsconfigured for the user equipment, (3) information about a logicalchannel of the user equipment, where the logical channel is a logicalchannel with a highest priority in all logical channels of the userequipment that have to-be-transmitted uplink data, (4) information abouta logical channel of the user equipment, where the logical channel isall logical channels of the user equipment that have to-be-transmitteduplink data, and (5) information about a logical channel of the userequipment, where the logical channel is all logical channels of the userequipment.

S4602. The second network device sends a first message to the firstnetwork device, where the first message includes an RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates a primary serving cell used by the user equipment in thesecond network device, and the RRC connection reconfiguration messageindicates an active BWP of the user equipment in the primary servingcell.

S4603. The first network device sends the RRC connection reconfigurationmessage to the user equipment, where the RRC connection reconfigurationmessage is used to indicate the primary serving cell that is of the userequipment and that is provided by the second network device and theactive BWP in the primary serving cell.

S4604. The user equipment sends a random access preamble to the secondnetwork device on the active BWP.

In this embodiment, the user equipment sends the preamble to the secondnetwork device on the active BWP.

54605. The user equipment receives, on the active BWP, an RAR messagesent by the second network device, where the RAR message includes orindicates a first BWP identifier.

54606. The user equipment activates a first BWP corresponding to the BWPidentifier.

S4607. The user equipment performs uplink transmission on the first BWPcorresponding to the first BWP identifier.

Herein, steps S4601 to S4607 are steps 4501 to 4505 in FIG. 45. Detailsare not described again.

In this embodiment, the user equipment receives the RRC connectionreconfiguration message sent by the first network device, where the RRCconnection reconfiguration message is used to indicate the primaryserving cell of the user equipment in the second network device and theactive BWP in the primary serving cell, the user equipment sends thepreamble to the second network device on the active BWP, the userequipment receives, on the active BWP, the RAR message and the first BWPidentifier that are sent by the second network device, and the userequipment performs uplink transmission on the first BWP corresponding tothe first BWP identifier. In this way, the user equipment can send thepreamble to the second network device based on the active BWP indicatedby the network device, and then the user equipment sends data orinformation to the network device based on the first BWP indicated bythe network device. The first BWP is consistent with a BWP indicated bya UL grant sent by the network device, so that uplink data can beeffectively transmitted by using the UL grant in the RAR message.

FIG. 47 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.47, the method is specifically as follows:

4701. A second network device receives a second message sent by a firstnetwork device.

The second message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation method, the information about the uplinkBWP includes at least one of the following: an identifier of the uplinkBWP, a parameter set of a subcarrier spacing and a cyclic prefix lengthof the uplink BWP, and a bandwidth value of the uplink BWP, theinformation about the BWP pair includes at least one of the following:an identifier of the BWP pair, a parameter set of a subcarrier spacingand a cyclic prefix length of the BWP pair, and a bandwidth value of theBWP pair, and the information about a logical channel includes at leastone of the following: an identifier of a logical channel, a parameterset, of a subcarrier spacing and a cyclic prefix length, to which eachlogical channel is mapped, a data radio bearer corresponding to eachlogical channel, and indication information, where the indicationinformation indicates whether each logical channel or each correspondingdata radio bearer has uplink data available for transmission.

4702. The second network device receives, on an active BWP, a randomaccess preamble sent by the user equipment, where the random accesspreamble is sent after the user equipment receives an RRC connectionreconfiguration message sent by the first network device, and the RRCconnection reconfiguration message is used to indicate the primaryserving cell under the second network device for the user equipment, andindicate an active BWP in the primary serving cell.

In an optional implementation method, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a second BWP identifier, anda BWP corresponding to the second BWP identifier is the active BWP.

In an optional implementation method, the RAR message includes a ULgrant, and the UL grant includes or indicates the BWP identifier.

4703. The second network device sends an RAR message to the userequipment on the active BWP, where the RAR message includes or indicatesa first BWP identifier, and the first BWP identifier corresponds to afirst BWP.

In an optional implementation method, a physical resource used foruplink transmission is a physical resource indicated by the UL grant.

In an optional implementation method, the first BWP is an uplink BWP,the active BWP includes an uplink BWP and a downlink BWP, and the firstBWP and the uplink BWP in the active BWP may be a same BWP, or may bedifferent BWPs.

In an optional implementation method, the first BWP is a BWP pairincluding an uplink BWP and a downlink BWP, the active BWP is a BWP pairincluding an uplink BWP and a downlink BWP, and the first BWP and theactive BWP may be a same BWP, or may be different BWPs.

For the method provided in this embodiment, refer to the methods in FIG.45 and FIG. 46. Details are not described again.

FIG. 48 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.48, the method is specifically as follows:

4801. User equipment receives an RRC connection reconfiguration messagesent by a first network device, where the RRC connection reconfigurationmessage is included in a first message sent by a second network deviceto the first network device, and the RRC connection reconfigurationmessage is used to indicate the primary serving cell under the secondnetwork device for the user equipment, and indicate an active BWP in theprimary serving cell.

In this embodiment, for this step, refer to step 4501 in FIG. 45.Details are not described again.

4802. The user equipment sends a random access preamble to the secondnetwork device on the active BWP.

In this embodiment, for this step, refer to step 4502 in FIG. 45.Details are not described again.

4803. The user equipment receives, on the active BWP, an RAR message anda BWP identifier that are sent by the second network device, where theRAR message includes a UL grant, the RAR message is scheduled by usingfirst DCI, and the BWP identifier is carried in the first DCI, or theuser equipment receives, on the active BWP, an RAR message and a BWPidentifier that are sent by the second network device, where the RARmessage includes a UL grant, the BWP identifier is carried in secondDCI, and the second DCI is DCI for instructing the terminal device toswitch a BWP, or the second DCI is DCI for instructing the terminaldevice to switch a pair of an uplink BWP and a downlink BWP.

4804. The user equipment activates a first BWP corresponding to the BWPidentifier.

In this embodiment, there are three cases as to whether the userequipment needs to activate the first BWP.

In a first case, if the BWP identifier is an identifier of the activeBWP in step 4801, the first BWP corresponding to the BWP is the activeBWP in step 4801, and it may be determined that the UL grant included inthe RAR message is a UL grant corresponding to the active BWP, in step4801, of the user equipment in a first serving cell. In this case, theuser equipment does not need to perform BWP switching, in other words,the first BWP is in an active state, and the user equipment does notneed to further activate the first BWP. In this case, the user equipmentmay send data or signaling to the network device on the active BWP ofthe first serving cell in step 4801 based on the UL grant in the RARmessage.

In a second case, if the BWP identifier is not an identifier of theactive BWP in step 4801, the first BWP corresponding to the BWP isdifferent from the active BWP in step 4801, and it may be determinedthat the UL grant included in the RAR message is a UL grantcorresponding to the first BWP of the user equipment in a first servingcell. In this case, the user equipment needs to switch to the first BWP,in other words, deactivate the active BWP in step 4801, and activate thefirst BWP. In this case, the user equipment may send data or signalingto the network device on the first BWP of the first serving cell basedon the UL grant in the RAR message.

In this step, in the second case, the user equipment needs to activatethe first BWP corresponding to the BWP identifier.

In addition, in the second case, after the user equipment determinesthat the RAR message is received, the user equipment needs to switch tothe first BWP when determining that an identifier that is of a preambleand that is included in the RAR message is an identifier of the preamblesent by the user equipment.

4805. The user equipment performs uplink transmission on the first BWPcorresponding to the first BWP identifier.

For this step, refer to step 4505 in FIG. 45. Details are not describedagain.

FIG. 49 is signaling of another random access method according to anembodiment of the present invention. As shown in FIG. 49, the method isspecifically as follows:

S4901. A first network device sends a second message to a second networkdevice, where the second message includes at least one of the followinginformation: (1) information about an uplink BWP or a BWP pair activatedby user equipment, (2) information about all uplink BWPs or BWP pairsconfigured for the user equipment, (3) information about a logicalchannel of the user equipment, where the logical channel is a logicalchannel with a highest priority in all logical channels of the userequipment that have to-be-transmitted uplink data, (4) information abouta logical channel of the user equipment, where the logical channel isall logical channels of the user equipment that have to-be-transmitteduplink data, and (5) information about a logical channel of the userequipment, where the logical channel is all logical channels of the userequipment.

S4902. The second network device sends a first message to the firstnetwork device, where the first message includes an RRC connectionreconfiguration message, the RRC connection reconfiguration messageindicates a primary serving cell used by the user equipment in thesecond network device, and the RRC connection reconfiguration messageindicates an active BWP of the user equipment in the primary servingcell.

S4903. The first network device sends the RRC connection reconfigurationmessage to the user equipment, where the RRC connection reconfigurationmessage is used to indicate the primary serving cell that is of the userequipment and that is provided by the second network device and theactive BWP in the primary serving cell.

S4904. The user equipment sends a random access preamble to the secondnetwork device on the active BWP.

In this embodiment, the user equipment sends the preamble to the secondnetwork device on the active BWP.

54905. The user equipment receives, on the active BWP, an RAR messageand a BWP identifier that are sent by the second network device, wherethe RAR message includes a UL grant, the RAR message is scheduled byusing first DCI, and the BWP identifier is carried in the first DCI, orthe user equipment receives, on the active BWP, an RAR message and a BWPidentifier that are sent by the second network device, where the RARmessage includes a UL grant, the BWP identifier is carried in secondDCI, and the second DCI is DCI for instructing the terminal device toswitch a BWP, or the second DCI is DCI for instructing the terminaldevice to switch a pair of an uplink BWP and a downlink BWP.

S4906. The user equipment activates a first BWP corresponding to the BWPidentifier.

S4907. The user equipment performs uplink transmission on the first BWPcorresponding to the first BWP identifier.

Herein, steps S4901 to S4907 are steps 4801 to 4805 in FIG. 48. Detailsare not described again.

In this embodiment, the user equipment receives the RRC connectionreconfiguration message sent by the first network device, where the RRCconnection reconfiguration message is used to indicate the primaryserving cell of the user equipment in the second network device and theactive BWP in the primary serving cell, the user equipment sends thepreamble to the second network device on the active BWP, the userequipment receives, on the active BWP, the RAR message and the first BWPidentifier that are sent by the second network device, and the userequipment performs uplink transmission on the first BWP corresponding tothe first BWP identifier. In this way, the user equipment can send thepreamble to the second network device based on the active BWP indicatedby the network device, and then the user equipment sends data orinformation to the network device based on the first BWP indicated bythe network device. The first BWP is consistent with a BWP indicated bythe UL grant sent by the network device, so that uplink data can beeffectively transmitted by using the UL grant in the RAR message.

FIG. 50 is a schematic flowchart of another random access methodaccording to an embodiment of the present invention. As shown in FIG.50, the method is specifically as follows:

5001. A second network device receives a second message sent by a firstnetwork device.

The second message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation method, the information about the uplinkBWP includes at least one of the following: an identifier of the uplinkBWP, a parameter set of a subcarrier spacing and a cyclic prefix lengthof the uplink BWP, and a bandwidth value of the uplink BWP, theinformation about the BWP pair includes at least one of the following:an identifier of the BWP pair, a parameter set of a subcarrier spacingand a cyclic prefix length of the BWP pair, and a bandwidth value of theBWP pair, and the information about a logical channel includes at leastone of the following: an identifier of a logical channel, a parameterset, of a subcarrier spacing and a cyclic prefix length, to which eachlogical channel is mapped, a data radio bearer corresponding to eachlogical channel, and indication information, where the indicationinformation indicates whether each logical channel or each correspondingdata radio bearer has uplink data available for transmission.

5002. The second network device receives, on an active BWP, a randomaccess preamble sent by the user equipment, where the random accesspreamble is sent after the user equipment receives an RRC connectionreconfiguration message sent by the first network device, and the RRCconnection reconfiguration message is used to indicate the primaryserving cell under the second network device for the user equipment, andindicate an active BWP in the primary serving cell.

In an optional implementation method, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a second BWP identifier, anda BWP corresponding to the second BWP identifier is the active BWP.

In an optional implementation method, the RAR message includes the ULgrant, and the UL grant includes or indicates the BWP identifier.

5003. The user equipment receives, on the active BWP, an RAR message anda BWP identifier that are sent by the second network device, where theRAR message includes a UL grant, the RAR message is scheduled by usingfirst DCI, and the BWP identifier is carried in the first DCI, or theuser equipment receives, on the active BWP, an RAR message and a BWPidentifier that are sent by the second network device, where the RARmessage includes a UL grant, the BWP identifier is carried in secondDCI, and the second DCI is DCI for instructing the terminal device toswitch a BWP, or the second DCI is DCI for instructing the terminaldevice to switch a pair of an uplink BWP and a downlink BWP.

In an optional implementation method, a physical resource used foruplink transmission is a physical resource indicated by the UL grant.

In an optional implementation method, a first BWP is an uplink BWP, theactive BWP includes an uplink BWP and a downlink BWP, and the first BWPand the uplink BWP in the active BWP may be a same BWP, or may bedifferent BWPs.

In an optional implementation method, a first BWP is a BWP pairincluding an uplink BWP and a downlink BWP, the active BWP is a BWP pairincluding an uplink BWP and a downlink BWP, and the first BWP and theactive BWP may be a same BWP, or may be different BWPs.

For the method provided in this embodiment, refer to the methods in FIG.48 and FIG. 49. Details are not described again.

FIG. 51 is a schematic structural diagram of user equipment according toan embodiment of this application. As shown in FIG. 51, the userequipment includes a receiving module 511, configured to receive controlsignaling sent by a network device, where the control signaling is usedto trigger the user equipment to perform a random access procedure, andthe control signaling includes or indicates a BWP identifier, and anaccess module 512, configured to initiate a random access procedurebased on the control signaling.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the access module 512 is specificallyconfigured to initiate the random access procedure on a BWPcorresponding to the BWP identifier.

In an optional implementation, the user equipment further includes anactivation module, configured to activate the BWP before the accessmodule 512 initiates the random access procedure based on the controlsignaling.

In an optional implementation, the BWP is an uplink BWP, and the accessmodule 512 includes a first sending submodule, configured to send arandom access preamble to the network device on the uplink BWP, a firstreceiving submodule, configured to receive a first RAR message sent bythe network device, where the first RAR message includes a first ULgrant, and a first transmission submodule, configured to perform uplinktransmission on the uplink BWP, where a physical resource used for theuplink transmission is a physical resource indicated by the first ULgrant.

In an optional implementation, the BWP is a BWP pair including an uplinkBWP and a downlink BWP, and the access module 512 includes a secondsending submodule, configured to send a random access preamble to thenetwork device on the uplink BWP of the BWP, a second receivingsubmodule, configured to receive a second RAR message sent by thenetwork device, where the second RAR message includes a second UL grant,and a second transmission submodule, configured to perform transmissionon the uplink BWP of the BWP, where a physical resource used for thetransmission is a physical resource indicated by the second UL grant.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the BWP identifier, or thecontrol signaling received by the user equipment in any serving cellincludes the BWP identifier, where at least two uplink BWPs areconfigured for the user equipment in at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs, or the control signaling received by the user equipmentin a secondary serving cell includes the BWP identifier, or the controlsignaling received by the user equipment in at least one secondaryserving cell includes the BWP identifier, where at least two uplink BWPsare configured for the user equipment in the at least one secondaryserving cell, and a random access channel is configured for each of theat least two uplink BWPs.

The user equipment in this embodiment may be configured to perform thetechnical solutions of the embodiments shown in FIG. 6 to FIG. 10 in theforegoing methods. Implementation principles and technical effects ofthe user equipment are similar to those in the foregoing embodiments,and details are not described herein again.

FIG. 52 is a schematic structural diagram of a network device accordingto an embodiment of this application. As shown in FIG. 52, the networkdevice includes a sending module 521, configured to send controlsignaling to user equipment, where the control signaling is used totrigger the user equipment to perform a random access procedure, and thecontrol signaling includes or indicates a BWP identifier.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, a BWP corresponding to the BWP identifieris an uplink BWP.

In an optional implementation, a BWP corresponding to the BWP identifieris a BWP pair including an uplink BWP and a downlink BWP.

The network device in this embodiment may be configured to perform thetechnical solutions of the embodiment shown in FIG. 11 in the foregoingmethods. Implementation principles and technical effects of the networkdevice are similar to those in the foregoing embodiment, and details arenot described herein again.

FIG. 53 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. As shown in FIG. 53, theuser equipment includes a first receiving module 531, configured toreceive an RAR message sent by a network device, where the RAR messageincludes or indicates a BWP identifier, and a transmission module 532,configured to perform uplink transmission on a first BWP correspondingto the BWP identifier.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In an optional implementation, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In an optional implementation, the user equipment further includes afirst activation module, configured to activate the first BWP before thetransmission module 532 performs uplink transmission on the first BWPcorresponding to the BWP identifier.

In an optional implementation, the user equipment further includes asecond receiving module, configured to before the first receiving module531 receives the RAR message sent by the network device, receive controlsignaling sent by the network device, where the control signaling isused to trigger the user equipment to perform a random access procedure,and a sending module, configured to send a random access preamble to thenetwork device on a second BWP.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the user equipment further includes asecond activation module, configured to activate the second BWP beforethe sending module sends the random access preamble to the networkdevice on the second BWP.

In an optional implementation, the control signaling includes anidentifier of the second BWP.

In an optional implementation, the control signaling received by theuser equipment in any serving cell includes the identifier of the secondBWP, or the control signaling received by the user equipment in anyserving cell includes the identifier of the second BWP, where at leasttwo uplink BWPs are configured for the user equipment in at least onesecondary serving cell, and a random access channel is configured foreach of the at least two uplink BWPs, or the control signaling receivedby the user equipment in a secondary serving cell includes theidentifier of the second BWP, or the control signaling received by theuser equipment in at least one secondary serving cell includes theidentifier of the second BWP, where at least two uplink BWPs areconfigured for the user equipment in the at least one secondary servingcell, and a random access channel is configured for each of the at leasttwo uplink BWPs.

In an optional implementation, the second BWP is a BWP of the userequipment in a first serving cell, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In an optional implementation, the first BWP and the second BWP areuplink BWPs, and the first BWP and the second BWP may be a same BWP, ormay be different BWPs. The first receiving module 531 is specificallyconfigured to receive, on a third BWP, the RAR message sent by thenetwork device, where the third BWP is a downlink BWP, where the thirdBWP is an active BWP in the second serving cell when the user equipmentreceives the control signaling in the first serving cell, or the thirdBWP is a BWP used when the user equipment receives the control signalingin the first serving cell.

In an optional implementation, the first BWP and the second BWP each area BWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Thefirst receiving module 531 is specifically configured to receive, on theuplink BWP of the second BWP, the RAR message sent by the networkdevice.

In an optional implementation, the first receiving module 531 isspecifically configured to receive, on a fourth BWP, the RAR messagesent by the network device, where the fourth BWP is a BWP pair includingan uplink BWP and a downlink BWP, where the fourth BWP is an active BWPin the second serving cell when the user equipment receives the controlsignaling in the first serving cell, or the fourth BWP is a BWP usedwhen the user equipment receives the control signaling in the firstserving cell.

In an optional implementation, if the fourth BWP is a BWP used when theuser equipment receives the control signaling in the first serving cell,the user equipment further includes a third activation module,configured to after the sending module sends the random access preambleto the network device on the second BWP, activate the fourth BWP, anddeactivate the second BWP.

The user equipment in this embodiment may be configured to perform thetechnical solutions of the embodiments shown in FIG. 12 to FIG. 15, orFIG. 17 and FIG. 18, or FIG. 20 and FIG. 21, or FIG. 23 and FIG. 24, orFIG. 26 and FIG. 27, or FIG. 29 and FIG. 30, or FIG. 32 and FIG. 33, orFIG. 35 and FIG. 36, or FIG. 38 and FIG. 39 in the foregoing methods.Implementation principles and technical effects of the user equipmentare similar to those in the foregoing embodiments, and details are notdescribed herein again.

FIG. 54 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. As shown in FIG. 54, thenetwork device includes a first sending module 541, configured to sendan RAR message to user equipment, where the RAR message includes orindicates a BWP identifier, and the BWP identifier corresponds to afirst BWP.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In an optional implementation, the network device further includes asecond sending module, configured to before the first sending module 541sends the RAR message to the user equipment, send control signaling tothe user equipment, where the control signaling is used to trigger theuser equipment to perform a random access procedure.

In an optional implementation, the control signaling is a PDCCH order.

In an optional implementation, the control signaling includes anidentifier of a second BWP.

In an optional implementation, the second BWP is a BWP in a firstserving cell of the user equipment, and the first serving cell is aserving cell used when the user equipment receives the controlsignaling, or the first serving cell is a serving cell scheduled byusing a second serving cell used when the user equipment receives thecontrol signaling.

In an optional implementation, the first BWP is an initial active BWP ofthe user equipment in the first serving cell, or the first BWP is afirst active BWP of the user equipment in the first serving cell, or thefirst BWP is a default BWP of the user equipment in the first servingcell, or the first BWP is a BWP configured by the network device for theuser equipment, and the first BWP is used by the user equipment toperform random access in the first serving cell, or the first BWP is aBWP configured by the network device for the user equipment, and thefirst BWP is a BWP used by the user equipment to perform contention freerandom access in the first serving cell, or the first BWP is a BWPactivated when the user equipment performs random access, or the firstBWP is a BWP activated when the user equipment performs contention freerandom access.

In an optional implementation, the first BWP and the second BWP areuplink BWPs, and the first BWP and the second BWP may be a same BWP, ormay be different BWPs. The first sending module 541 is specificallyconfigured to send the RAR message to the user equipment on a third BWP,where the third BWP is a downlink BWP, where the third BWP is an activeBWP in the second serving cell when the user equipment receives thecontrol signaling in the first serving cell, or the third BWP is a BWPused when the user equipment receives the control signaling in the firstserving cell.

In an optional implementation, the first BWP and the second BWP each area BWP pair including an uplink BWP and a downlink BWP, and the first BWPand the second BWP may be a same BWP, or may be different BWPs. Thefirst sending module 541 is specifically configured to send the RARmessage to the user equipment on the uplink BWP of the second BWP.

In an optional implementation, the first sending module 541 isspecifically configured to send the RAR message to the user equipment ona fourth BWP, where the fourth BWP is a BWP pair including an uplink BWPand a downlink BWP, where the fourth BWP is an active BWP in the secondserving cell when the user equipment receives the control signaling inthe first serving cell, or the fourth BWP is a BWP used when the userequipment receives the control signaling in the first serving cell.

The network device in this embodiment may be configured to perform thetechnical solutions of the embodiment shown in FIG. 16, FIG. 19, FIG.22, FIG. 25, FIG. 28, FIG. 34, FIG. 37, or FIG. 40 in the foregoingmethods. Implementation principles and technical effects of the networkdevice are similar to those in the foregoing embodiment, and details arenot described herein again.

FIG. 55 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. As shown in FIG. 55, theuser equipment includes a receiving module 551, configured to receive anRRC connection reconfiguration message sent by a first network device,where the RRC connection reconfiguration message is included in a firstmessage sent by a second network device to the first network device, andthe RRC connection reconfiguration message is used to indicate theprimary serving cell under the second network device for the userequipment, and indicate an active BWP in the primary serving cell, andan access module 552, configured to initiate a random access procedureon the active BWP.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

In an optional implementation, the active BWP includes an uplink BWP anda downlink BWP, and the access module 552 includes a first sendingsubmodule, configured to send a random access preamble to the secondnetwork device on the uplink BWP in the active BWP, a first receivingsubmodule, configured to receive, by the user equipment on the downlinkBWP in the active BWP, an RAR message sent by the second network device,where the RAR message includes a UL grant, and a first transmissionsubmodule, configured to perform, by the user equipment, uplinktransmission on the uplink BWP in the active BWP, where a physicalresource used for the uplink transmission is a physical resourceindicated by the UL grant.

In an optional implementation, the active BWP is a BWP pair including anuplink BWP and a downlink BWP, and the access module 552 includes asecond sending submodule, configured to send a random access preamble tothe second network device on the uplink BWP of the BWP pair, a secondreceiving submodule, configured to receive, on the downlink BWP of theBWP pair, an RAR message sent by the second network device, where theRAR message includes a UL grant, and a second transmission submodule,configured to perform uplink transmission on the uplink BWP of the BWPpair, where a physical resource used for the uplink transmission is aphysical resource indicated by the UL grant.

In an optional implementation, the first message is a response messagesent by the second network device after the second network devicereceives a second message sent by the first network device, and thesecond message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by the userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

The user equipment in this embodiment may be configured to perform thetechnical solutions of the embodiments shown in FIG. 41 to FIG. 43 inthe foregoing methods. Implementation principles and technical effectsof the user equipment are similar to those in the foregoing embodiments,and details are not described herein again.

FIG. 56 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. As shown in FIG. 56, thenetwork device includes a receiving module 561, configured to receive afirst message sent by a second network device, where the first messageincludes an RRC connection reconfiguration message, and a first sendingmodule 562, configured to send the RRC connection reconfigurationmessage to user equipment, where the RRC connection reconfigurationmessage is used to indicate the primary serving cell under the secondnetwork device for the user equipment, and indicate an active BWP in theprimary serving cell.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a first BWP identifier, anda BWP corresponding to the first BWP identifier is the active BWP.

In an optional implementation, the active BWP includes an uplink BWP anda downlink BWP.

In an optional implementation, the active BWP is a BWP pair including anuplink BWP and a downlink BWP.

In an optional implementation, the first network device further includesa second sending module, configured to before the receiving module 561receives the first message sent by the second network device, send asecond message to the second network device, where the second messageincludes at least one of the following information: information about anuplink BWP or a BWP pair activated by the user equipment, informationabout all uplink BWPs or BWP pairs configured for the user equipment,and information about a logical channel of the user equipment, where thelogical channel is a logical channel with a highest priority in alllogical channels of the user equipment that have to-be-transmitteduplink data, or the logical channel is all logical channels of the userequipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

The network device in this embodiment may be configured to perform thetechnical solutions of the embodiment shown in FIG. 44 in the foregoingmethods. Implementation principles and technical effects of the networkdevice are similar to those in the foregoing embodiment, and details arenot described herein again.

FIG. 57 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. As shown in FIG. 57, theuser equipment includes a first receiving module 571, configured toreceive an RRC connection reconfiguration message sent by a firstnetwork device, where the RRC connection reconfiguration message isincluded in a first message sent by a second network device to the firstnetwork device, and the RRC connection reconfiguration message is usedto indicate the primary serving cell under the second network device forthe user equipment, and indicate an active BWP in the primary servingcell, a sending module 572, configured to send a random access preambleto the second network device on the active BWP, a second receivingmodule 573, configured to receive, on the active BWP, an RAR messagesent by the second network device, where the RAR message includes orindicates a first BWP identifier, and a transmission module 574,configured to perform uplink transmission on a first BWP correspondingto the first BWP identifier.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a second BWP identifier, anda BWP corresponding to the second BWP identifier is the active BWP.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In an optional implementation, a physical resource used for the uplinktransmission is a physical resource indicated by the UL grant.

In an optional implementation, the user equipment further includes anactivation module, configured to activate the first BWP before thetransmission module 574 performs uplink transmission on the first BWPcorresponding to the first BWP identifier.

In an optional implementation, the first BWP is an uplink BWP, theactive BWP includes an uplink BWP and a downlink BWP, and the first BWPand the uplink BWP in the active BWP may be a same BWP, or may bedifferent BWPs, or the first BWP is a BWP pair including an uplink BWPand a downlink BWP, the active BWP is a BWP pair including an uplink BWPand a downlink BWP, and the first BWP and the active BWP may be a sameBWP, or may be different BWPs.

In an optional implementation, the first message is a response messagesent by the second network device after the second network devicereceives a second message sent by the first network device, and thesecond message includes at least one of the following information:information about an uplink BWP or a BWP pair activated by the userequipment, information about all uplink BWPs or BWP pairs configured forthe user equipment, and information about a logical channel of the userequipment, where the logical channel is a logical channel with a highestpriority in all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment that have to-be-transmitted uplink data,or the logical channel is all logical channels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

The user equipment in this embodiment may be configured to perform thetechnical solutions of the embodiments shown in FIG. 45 and FIG. 46, orFIG. 48 and FIG. 49 in the foregoing methods. Implementation principlesand technical effects of the user equipment are similar to those in theforegoing embodiments, and details are not described herein again.

FIG. 58 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. As shown in FIG. 58, thenetwork device includes a first receiving module 581, configured toreceive, on an active BWP, a random access preamble sent by userequipment, where the random access preamble is sent after the userequipment receives an RRC connection reconfiguration message sent by afirst network device, and the RRC connection reconfiguration message isused to indicate the primary serving cell under the second networkdevice for the user equipment, and indicate an active BWP in the primaryserving cell, and a sending module 582, configured to send an RARmessage to the user equipment on the active BWP, where the RAR messageincludes or indicates a first BWP identifier, and the first BWPidentifier corresponds to a first BWP.

In an optional implementation, the active BWP is a BWP in commonconfiguration information of the primary serving cell, or the RRCconnection reconfiguration message includes a second BWP identifier, anda BWP corresponding to the second BWP identifier is the active BWP.

In an optional implementation, the RAR message includes a UL grant, andthe UL grant includes or indicates the BWP identifier.

In an optional implementation, a physical resource used for uplinktransmission is a physical resource indicated by the UL grant.

In an optional implementation, the first BWP is an uplink BWP, theactive BWP includes an uplink BWP and a downlink BWP, and the first BWPand the uplink BWP in the active BWP may be a same BWP, or may bedifferent BWPs, or the first BWP is a BWP pair including an uplink BWPand a downlink BWP, the active BWP is a BWP pair including an uplink BWPand a downlink BWP, and the first BWP and the active BWP may be a sameBWP, or may be different BWPs.

In an optional implementation, the second network device furtherincludes a second receiving module, configured to before the firstreceiving module receives, on the active BWP, the random access preamblesent by the user equipment, receive a second message sent by the firstnetwork device, where the second message includes at least one of thefollowing information: information about an uplink BWP or a BWP pairactivated by the user equipment, information about all uplink BWPs orBWP pairs configured for the user equipment, and information about alogical channel of the user equipment, where the logical channel is alogical channel with a highest priority in all logical channels of theuser equipment that have to-be-transmitted uplink data, or the logicalchannel is all logical channels of the user equipment that haveto-be-transmitted uplink data, or the logical channel is all logicalchannels of the user equipment.

In an optional implementation, the information about the uplink BWPincludes at least one of the following: an identifier of the uplink BWP,a parameter set of a subcarrier spacing and a cyclic prefix length ofthe uplink BWP, and a bandwidth value of the uplink BWP, the informationabout the BWP pair includes at least one of the following: an identifierof the BWP pair, a parameter set of a subcarrier spacing and a cyclicprefix length of the BWP pair, and a bandwidth value of the BWP pair,and the information about a logical channel includes at least one of thefollowing: an identifier of a logical channel, a parameter set, of asubcarrier spacing and a cyclic prefix length, to which each logicalchannel is mapped, a data radio bearer corresponding to each logicalchannel, and indication information, where the indication informationindicates whether each logical channel or each corresponding data radiobearer has uplink data available for transmission.

The network device in this embodiment may be configured to perform thetechnical solutions of the embodiment shown in FIG. 47 or FIG. 50 in theforegoing methods. Implementation principles and technical effects ofthe network device are similar to those in the foregoing embodiment, anddetails are not described herein again.

FIG. 59 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. The user equipment maybe configured to perform the actions or steps of the user equipment inthe embodiments shown in FIG. 6 to FIG. 10. The user equipmentspecifically includes a receiver 5901, a transmitter 5902, a processor5903, and a memory 5904.

The components in the user equipment are configured to implement theactions in the embodiments shown in FIG. 6 to FIG. 10. Details are notdescribed again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more application-specific integrated circuits (ASIC),one or more microprocessors (DSP), or one or more field programmablegate arrays (FPGA).

FIG. 60 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. The network device maybe configured to perform the actions or steps of the user equipment inthe embodiment shown in FIG. 11. The network device specificallyincludes a receiver 6001, a transmitter 6002, a processor 6003, and amemory 6004.

The components in the user equipment are configured to implement theactions in the embodiment shown in FIG. 11. Details are not describedagain.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

The processor 6003 may be alternatively a controller, and is representedas “Controller/Processor 6003” in FIG. 60. The transmitter 6002 and thereceiver 6001 are configured to support the network device in sendinginformation to or receiving information from the terminal device in theforegoing embodiments and support radio communication between theterminal device and another terminal device. The processor 6003 performsvarious functions of communicating with the terminal device.

Further, the network device may further include the memory 6004, and thememory 6004 is configured to store program code and data of the networkdevice. In addition, the network device may further include acommunications interface 6005. The communications interface 6005 isconfigured to support the network device in communicating with anothernetwork entity.

The processor 6003 is, for example, a central processing unit (CPU), ormay be configured as one or more integrated circuits for implementingthe foregoing methods, for example, one or more ASICs, one or more DSPs,or one or more FPGAs. The memory 6004 may be one memory, or may be ageneral term for a plurality of storage elements.

FIG. 61 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. The user equipment maybe configured to perform the actions or steps of the user equipment inthe embodiments shown in FIG. 12 to FIG. 15, or FIG. 17 and FIG. 18, orFIG. 20 and FIG. 21, or FIG. 23 and FIG. 24, or FIG. 26 and FIG. 27, orFIG. 29 and FIG. 30, or FIG. 32 and FIG. 33, or FIG. 35 and FIG. 36, orFIG. 38 and FIG. 39. The user equipment specifically includes a receiver6101, a transmitter 6102, a processor 6103, and a memory 6104.

The components in the user equipment are configured to implement theactions in the embodiments shown in FIG. 12 to FIG. 15, or FIG. 17 andFIG. 18, or FIG. 20 and FIG. 21, or FIG. 23 and FIG. 24, or FIG. 26 andFIG. 27, or FIG. 29 and FIG. 30, or FIG. 32 and FIG. 33, or FIG. 35 andFIG. 36, or FIG. 38 and FIG. 39. Details are not described again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

FIG. 62 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. The network device maybe configured to perform the actions or steps of the user equipment inthe embodiment shown in FIG. 16, FIG. 19, FIG. 22, FIG. 25, FIG. 28,FIG. 34, FIG. 37, or FIG. 40. The network device specifically includes areceiver 6201, a transmitter 6202, a processor 6203, and a memory 6204.

The components in the user equipment are configured to implement theactions in the embodiment shown in FIG. 16, FIG. 19, FIG. 22, FIG. 25,FIG. 28, FIG. 34, FIG. 37, or FIG. 40. Details are not described again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

The processor 6203 may be alternatively a controller, and is representedas “Controller/Processor 6203” in FIG. 62. The transmitter 6202 and thereceiver 6201 are configured to support the network device in sendinginformation to or receiving information from the terminal device in theforegoing embodiments and support radio communication between theterminal device and another terminal device. The processor 6203 performsvarious functions of communicating with the terminal device.

Further, the network device may further include the memory 6204, and thememory 6204 is configured to store program code and data of the networkdevice. In addition, the network device may further include acommunications interface 6205. The communications interface 6205 isconfigured to support the network device in communicating with anothernetwork entity.

The processor 6203 is, for example, a central processing unit (CPU), ormay be configured as one or more integrated circuits for implementingthe foregoing methods, for example, one or more ASICs, one or more DSPs,or one or more FPGAs. The memory 6204 may be one memory, or may be ageneral term for a plurality of storage elements.

FIG. 63 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. The user equipment maybe configured to perform the actions or steps of the user equipment inthe embodiments shown in FIG. 41 to FIG. 43. The user equipmentspecifically includes a receiver 6301, a transmitter 6302, a processor6303, and a memory 6304.

The components in the user equipment are configured to implement theactions in the embodiments shown in FIG. 41 to FIG. 43. Details are notdescribed again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

FIG. 64 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. The network device maybe configured to perform the actions or steps of the user equipment inthe embodiment shown in FIG. 44. The network device specificallyincludes a receiver 6401, a transmitter 6402, a processor 6403, and amemory 6404.

The components in the user equipment are configured to implement theactions in the embodiment shown in FIG. 44. Details are not describedagain.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

The processor 6403 may be alternatively a controller, and is representedas “Controller/Processor 6403” in FIG. 64. The transmitter 6402 and thereceiver 6401 are configured to support the network device in sendinginformation to or receiving information from the terminal device in theforegoing embodiments and support radio communication between theterminal device and another terminal device. The processor 6403 performsvarious functions of communicating with the terminal device.

Further, the network device may further include the memory 6404, and thememory 6404 is configured to store program code and data of the networkdevice. In addition, the network device may further include acommunications interface 6405. The communications interface 6405 isconfigured to support the network device in communicating with anothernetwork entity.

The processor 6403 is, for example, a central processing unit (CPU), ormay be configured as one or more integrated circuits for implementingthe foregoing methods, for example, one or more ASICs, one or more DSPs,or one or more FPGAs. The memory 6404 may be one memory, or may be ageneral term for a plurality of storage elements.

FIG. 65 is a schematic structural diagram of another user equipmentaccording to an embodiment of this application. The user equipment maybe configured to perform the actions or steps of the user equipment inthe embodiments shown in FIG. 45 and FIG. 46, or FIG. 48 and FIG. 49.The user equipment specifically includes a receiver 6501, a transmitter6502, a processor 6503, and a memory 6504.

The components in the user equipment are configured to implement theactions in the embodiments shown in FIG. 45 and FIG. 46, or FIG. 48 andFIG. 49. Details are not described again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

FIG. 66 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. The network device maybe configured to perform the actions or steps of the user equipment inthe embodiment shown in FIG. 47 or FIG. 50. The network devicespecifically includes a receiver 6601, a transmitter 6602, a processor6603, and a memory 6604.

The components in the user equipment are configured to implement theactions in the embodiment shown in FIG. 47 or FIG. 50. Details are notdescribed again.

In the embodiments of the present invention, reference may be made toeach other for the foregoing embodiments. Same or similar steps andnouns are not described again.

The processor 6603 may be alternatively a controller, and is representedas “Controller/Processor 6603” in FIG. 66. The transmitter 6602 and thereceiver 6601 are configured to support the network device in sendinginformation to or receiving information from the terminal device in theforegoing embodiments and support radio communication between theterminal device and another terminal device. The processor 6603 performsvarious functions of communicating with the terminal device.

Further, the network device may further include the memory 6604, and thememory 6604 is configured to store program code and data of the networkdevice. In addition, the network device may further include acommunications interface 6605. The communications interface 6605 isconfigured to support the network device in communicating with anothernetwork entity.

The processor 6603 is, for example, a central processing unit (CPU), ormay be configured as one or more integrated circuits for implementingthe foregoing methods, for example, one or more ASICs, one or more DSPs,or one or more FPGAs. The memory 6604 may be one memory, or may be ageneral term for a plurality of storage elements.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, all or some of the embodiments maybe implemented in a form of a computer program product. The computerprogram product includes one or more computer instructions. When thecomputer program instructions are loaded and executed on a computer, allor some of the procedures or functions according to the embodiments ofthis application are generated. The computer may be a general-purposecomputer, a dedicated computer, a computer network, or anotherprogrammable apparatus. The computer instructions may be stored in acomputer readable storage medium or may be transmitted from a computerreadable storage medium to another computer readable storage medium. Forexample, the computer instructions may be transmitted from a website,computer, server, or data center to another website, computer, server,or data center in a wired (for example, a coaxial cable, an opticalfiber, or a digital subscriber line (DSL)) or wireless (for example,infrared, radio, or microwave) manner. The computer readable storagemedium may be any usable medium accessible to a computer, or a datastorage device, such as a server or a data center, integrating one ormore usable media. The usable medium may be a magnetic medium (forexample, a floppy disk, a hard disk, or a magnetic tape), an opticalmedium (for example, a DVD), a semiconductor medium (for example, asolid state disk (SSD)), or the like.

A person skilled in the art should be aware that in the foregoing one ormore examples, functions described in the embodiments of thisapplication may be implemented by hardware, software, firmware, or anycombination thereof. When this application is implemented by software,these functions may be stored in a computer readable medium ortransmitted as one or more instructions or code in the computer readablemedium. The computer readable medium includes a computer storage mediumand a communications medium, where the communications medium includesany medium that enables a computer program to be transmitted from oneplace to another. The storage medium may be any usable medium accessibleto a general-purpose or dedicated computer.

The embodiments of this application are applied to a 5G communicationssystem or another system that may occur in the future. For ease ofunderstanding by a person skilled in the art, the following describessome terms in this application. It should be noted that a name of anetwork device and a name of a terminal may change when the solutions inthe embodiments of this application are applied to the 5G system oranother system that may occur in the future, but this does not affectimplementation of the solutions in the embodiments of this application.

(1) A terminal device, also referred to as a terminal or user equipment,is a device providing a user with voice and/or data connectivity, forexample, a handheld device or an in-vehicle device with a wirelessconnection function. Common terminal devices include, for example, amobile phone, a tablet computer, a notebook computer, a palmtopcomputer, a mobile Internet device (MID), and a wearable device, wherethe wearable device is, for example, a smartwatch, a smart band, or apedometer.

(2) A network device, also referred to as a radio access network (RAN)device, is a device for connecting a terminal device to a wirelessnetwork. There are network devices of various communication standards.For example, the network devices include but are not limited to a basestation, an evolved NodeB (evolved Node B, eNB), a radio networkcontroller (RNC), a NodeB (Node B, NB), a network device controller(BSC), a network device transceiver station (BTS), a home network device(for example, a home evolved NodeB or a home Node B, HNB), a basebandunit (Unit, BBU), and the like.

(3) In terms of a bandwidth part (BWP), when bandwidth of a cell iswide, a terminal device may operate only on a part of bandwidth of thecell. Each part of bandwidth of the cell is referred to as one BWP.

(4) There are network devices of various frequency standards. Forexample, the network devices include but are not limited to alow-frequency network device and a high-frequency network device.

(5) “A plurality of” means two or more, and another quantifier issimilar to this. The term “and/or” describes an association relationshipbetween associated objects and represents that three relationships mayexist. For example, A and/or B may represent the following three cases:Only A exists, both A and B exist, and only B exists. The character “/”usually indicates an “or” relationship between the associated objects.

FIG. 67 is a schematic diagram of an application scenario according toan embodiment of this application. A networking architecture shown inFIG. 67 mainly includes a network device 05 and a terminal device 06.The terminal device 05 may communicate with the network device 06. Inthis application, the network device may configure at least one downlinkBWP and at least one uplink BWP for one terminal device. The at leastone downlink BWP includes a default downlink BWP, and downlink bandwidthcorresponding to the default downlink BWP is relatively narrow.Therefore, when the terminal device transmits data on the defaultdownlink BWP, the terminal device only needs to monitor downlink controlinformation on a narrowband, and only needs to perform blind detectionin relatively small search space, thereby reducing power consumption ofthe terminal device. The terminal device may control the terminal deviceto fall back to the default downlink BWP to operate, to reduce powerconsumption of the terminal device. A timer is set for the terminaldevice. The timer is a timer for controlling the terminal device to fallback to a default downlink BWP. When the terminal device operates on anactive downlink BWP, the terminal device starts a timer, so that thetimer is started to run, where the active downlink BWP is not a defaultdownlink BWP. When the timer expires, it indicates that there has beenno downlink scheduling for the terminal device in a period of time. Inthis case, the terminal device does not need to perform datacommunication on wide bandwidth, but only needs to operate on narrowbandwidth. Therefore, the terminal device automatically switches to adefault downlink BWP to operate, where the default downlink BWP is adownlink BWP activated by the terminal device.

In a carrier aggregation scenario, it is specified in a current standardthat when a secondary serving cell is configured, a timer associatedwith the secondary serving cell and a default downlink BWP also need tobe configured. A network device sends an RRC connection reconfigurationmessage to a terminal device. The RRC connection reconfiguration messageis used to instruct to configure or reconfigure a secondary servingcell, and the RRC connection reconfiguration message indicates adownlink BWP and/or an uplink BWP that are or is first activated when asecondary serving cell is activated. The first active downlink BWP maynot be a default downlink BWP. It can be learned that when a secondaryserving cell is activated in an existing activation manner, it may bedirectly considered that a first downlink BWP and/or a first uplink BWPare or is also activated.

The following describes an operating mechanism of the timer: When theterminal device switches from a current active downlink BWP to anotheractive downlink BWP, the terminal device starts the timer, where theanother active downlink BWP is not a default downlink BWP. When theterminal device successfully obtains downlink control informationthrough decoding on the current active downlink BWP, and schedules aphysical downlink shared channel (PDSCH) by using the downlink controlinformation, the terminal device restarts the timer. When the timerexpires, the terminal device switches from the current active downlinkBWP to the default downlink BWP, and then the terminal device operateson the default downlink BWP.

It should be noted that the terms used in the embodiments of thisapplication may be mutually referenced, and details are not describedagain.

FIG. 68 is a schematic flowchart of a timer handling method according toan embodiment of the present invention. As shown in FIG. 2, the methodis specifically as follows:

101 c. A terminal device receives a physical downlink control channelorder (PDCCH) message sent by a network device, where a timer of theterminal device is running, and the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP.

In this embodiment, when the terminal device loses uplinksynchronization, and the terminal device receives downlink data, thenetwork device may send the PDCCH order message to the terminal device.The PDCCH order message is used to trigger the terminal device toperform a contention free random access procedure. Through the randomaccess procedure, the terminal device may implement uplinksynchronization with the network device again and then receive downlinkdata sent by the network device.

The terminal device maintains a timer. The timer is used for timing, andthe timer has specified duration. When duration for which the timer runsis equal to or exceeds the specified duration, it is considered that thetimer expires. In the prior art, if the terminal device determines thatthe timer expires, the terminal device performs BWP switching, in otherwords, the terminal device switches from a current active downlink BWPto a default downlink BWP. Optionally, the timer may be referred to as aBWP fallback timer.

In this embodiment, after the terminal device receives the PDCCH ordermessage sent by the network device, if the terminal device performs datacommunication on an active downlink BWP, and the active downlink BWP isnot a default downlink BWP, the terminal device may determine that thetimer of the terminal device is running.

102 c. The terminal device starts or restarts the timer.

In this embodiment, after step 101 c, after the terminal device receivesthe PDCCH order message sent by the network device, it indicates thatthe network device is to perform data communication with the terminaldevice. In this case, if the terminal device needs to still operate on adownlink BWP, and the downlink BWP is not a default downlink BWP, theterminal device needs to start or restart the timer.

A process in which the terminal device restarts the timer is as follows:The terminal device resets a value of the timer to an initial value, andthen the terminal device starts the timer.

In an optional implementation, the PDCCH order message includes anidentifier of a downlink BWP, and the downlink BWP indicated by theidentifier of the downlink BWP is not a default downlink BWP.

In this embodiment, the PDCCH order message sent by the network devicecarries an identifier of a downlink BWP, and the downlink BWP is not adefault downlink BWP. In this case, in step 102 c, the PDCCH ordermessage indicates that the terminal device needs to perform downlink BWPswitching. In step 102 c, the terminal device needs to switch to thedownlink BWP corresponding to the identifier of the downlink BWP, toperform data communication, and also needs to start or restart thetimer.

Alternatively, the PDCCH order message sent by the network device doesnot carry an identifier of a downlink BWP. In this case, in step 102 c,the terminal device does not need to perform downlink BWP switching, andthe terminal device still activates a downlink BWP used in a previousoperation, and also starts or restarts the timer.

FIG. 69 is a signaling diagram of a timer handling method according toan embodiment of the present invention. As shown in FIG. 69, the methodis specifically as follows:

S11 c. A network device sends a PDCCH order message to a terminaldevice, where a timer of the terminal device is running, and the timeris a timer used by the terminal device to switch from an active downlinkBWP to a default downlink BWP.

S12 c. The terminal device starts or restarts the timer.

In an optional implementation, the PDCCH order message includes anidentifier of a downlink BWP, and the downlink BWP indicated by theidentifier of the downlink BWP is not a default downlink BWP.

Herein, step 101 c in FIG. 68 is implemented in step S11 c. For S12 c,refer to step 102 c in FIG. 68. Details are not described again.

In this embodiment, the terminal device receives the PDCCH order messagesent by the network device, where the timer of the terminal device isrunning, and the timer is a timer used by the terminal device to switchfrom an active downlink BWP to a default downlink BWP, and the terminaldevice starts or restarts the timer. Therefore, when the timer of theterminal device is running, after the PDCCH order message sent by thenetwork device is received, it is considered whether the timer is to bestarted or restarted. In this way, an operating scenario of the timer isprovided.

FIG. 70 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.70, the method is specifically as follows:

201 c. A terminal device receives an indication message sent by anetwork device, where the indication message is used to instruct theterminal device to activate at least one secondary serving cell.

In this embodiment, the network device sends the indication message tothe terminal device, where the indication message is used to instructthe terminal device to activate one or more secondary serving cells.

In an optional implementation, the indication message is an activatecommand. The activate command may be a MAC CE for instructing toactivate at least one secondary serving cell.

In an optional implementation, the secondary serving cell is in aninactive state.

In this embodiment, in step 201 c, although the indication message isused to instruct the terminal device to activate the at least onesecondary serving cell, only some of the at least one secondary servingcell may be in an inactive state, or each of the at least one secondaryserving cell is in an inactive state.

202 c. The terminal device starts or restarts a timer associated withthe secondary serving cell, where the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP.

In this embodiment, at least one secondary serving cell is configuredfor the terminal device, and each secondary serving cell is associatedwith a timer. The timer is used for timing, and the timer has specifiedduration. When duration for which the timer runs is equal to or exceedsthe specified duration, it is considered that the timer expires. In theprior art, if the terminal device determines that the timer expires, theterminal device performs BWP switching, in other words, the terminaldevice switches from a current active downlink BWP to a default downlinkBWP in a current secondary serving cell. Optionally, the timer may bereferred to as a BWP fallback timer.

In this step, after step 201 c, after the terminal device receives theindication message, the terminal device may start or restart the timerassociated with the serving cell.

Specifically, after the terminal device receives the indication messagesent by the network device, the terminal device may start or restart atimer associated with each secondary serving cell indicated by theindication message. For example, the terminal device starts or restartsa timer associated with each secondary serving cell indicated by theindication message, or the terminal device starts or restarts a timerassociated with some of a plurality of secondary serving cells indicatedby the indication message.

Alternatively, after the terminal device receives the indication messagesent by the network device, because the indication message indicates theat least one secondary serving cell, the terminal device starts orrestarts only a timer of a secondary serving cell in an inactive statein the at least one secondary serving cell.

In an optional implementation, before step 201 c, the method may furtherinclude the following step:

Step 203 c: The terminal device receives an RRC message sent by thenetwork device, where the RRC message includes indication information,the indication information is used to instruct to add or modify the atleast one secondary serving cell, the RRC message further includes afirst downlink BWP of the secondary serving cell, the first downlink BWPis a downlink BWP that is first activated when the secondary servingcell is activated, and the first downlink BWP is not a default downlinkBWP.

In this embodiment, the network device first sends the RRC message tothe terminal device. Optionally, the RRC message may be an RRCconnection reconfiguration message. The RRC message includes theindication message, and the indication message is used to instruct theterminal device to add or modify the at least one secondary servingcell. In addition, the RRC message further includes first downlink BWPsof one or more of the at least one secondary serving cell. In otherwords, although the RRC message is used to instruct the terminal deviceto add or modify the at least one secondary serving cell, the RRCmessage may indicate first downlink BWPs of only one or more of the atleast one secondary serving cell.

In addition, a first downlink BWP of a secondary serving cell is adownlink BWP that is first activated when the terminal device activesthe secondary serving cell, and the first downlink BWP is not a defaultdownlink BWP.

For example, the network device sends an RRC message to the terminaldevice, the RRC message includes indication information, and theindication information is used to instruct to add or modify a secondaryserving cell 1, a secondary serving cell 2, a secondary serving cell 3,and a secondary serving cell 4, and the RRC message further includes afirst downlink BWP 1 of the secondary serving cell 2, the first downlinkBWP 1 is a downlink BWP 1 that is first activated when the secondaryserving cell 2 is activated, and the first downlink BWP 1 is not adefault downlink BWP.

For another example, the network device sends an RRC message to theterminal device, the RRC message includes indication information, andthe indication information is used to instruct to add or modify asecondary serving cell 1, a secondary serving cell 2, a secondaryserving cell 3, and a secondary serving cell 4, and the RRC messagefurther includes a first downlink BWP 1 of the secondary serving cell 2and a first downlink BWP 2 of the secondary serving cell 4, the firstdownlink BWP 1 is a downlink BWP that is first activated when thesecondary serving cell 2 is activated, the first downlink BWP 2 is adownlink BWP that is first activated when the secondary serving cell 4is activated, and neither the first downlink BWP 1 nor the firstdownlink BWP 2 is a default downlink BWP.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step 202 c specifically includes instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to start or restart the timerassociated with the secondary serving cell.

In this embodiment, if the timer associated with the secondary servingcell is a timer maintained by the physical layer of the terminal device,in step 202 c, the MAC layer of the terminal device sends an instructioncommand to the physical layer of the terminal device, so that thephysical layer of the terminal device starts or restarts the timerassociated with the secondary serving cell.

FIG. 71 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.71, the method is specifically as follows:

S22 c. A network device sends an RRC message to a terminal device, wherethe RRC message includes indication information, the indicationinformation is used to instruct to add or modify at least one secondaryserving cell, the RRC message further includes a first downlink BWP ofthe secondary serving cell, the first downlink BWP is a downlink BWPthat is first activated when the secondary serving cell is activated,and the first downlink BWP is not a default downlink BWP.

S21 c. The network device sends an indication message to the terminaldevice, where the indication message is used to instruct the terminaldevice to activate at least one secondary serving cell.

In an optional implementation, the indication message is an activatecommand. The activate command may be a MAC CE for instructing toactivate at least one secondary serving cell.

In an optional implementation, the secondary serving cell is in aninactive state.

S23 c. The terminal device starts or restarts a timer associated withthe secondary serving cell, where the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step S23 specifically includes instructing, by the terminaldevice by using a MAC layer of the terminal device, the physical layerof the terminal device to start or restart the timer associated with thesecondary serving cell.

Herein, step 201 c in FIG. 70 is implemented in step S21 c, step 203 cin FIG. 70 is implemented in step S22 c, and step 202 c in FIG. 70 isimplemented in step S23 c. Details are not described again.

In this embodiment, the terminal device receives the indication messagesent by the network device, where the indication message is used toinstruct the terminal device to activate the at least one secondaryserving cell, and the terminal device starts or restarts the timerassociated with the secondary serving cell, where the timer is a timerused by the terminal device to switch from an active downlink BWP to adefault downlink BWP. Therefore, when the terminal device receives theindication message that is sent by the network device and that is usedto instruct to activate the at least one secondary serving cell, it isconsidered whether the terminal device is to start or restart the timerassociated with the secondary serving cell. In this way, an operatingscenario of the timer is provided.

FIG. 72 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.72, the method is specifically as follows:

301 c. A terminal device receives an indication message sent by anetwork device, where the indication message is used to instruct theterminal device to deactivate at least one secondary serving cell, atimer associated with the secondary serving cell is running, and thetimer is a timer used by the terminal device to switch from an activedownlink BWP to a default downlink BWP.

In an optional implementation, the indication message is a deactivatecommand. The deactivate command may be a MAC CE for instructing todeactivate at least one secondary serving cell.

In this embodiment, at least one secondary serving cell is configuredfor the terminal device, and each secondary serving cell is associatedwith a timer. The timer is used for timing, and the timer has specifiedduration. When duration for which the timer runs is equal to or exceedsthe specified duration, it is considered that the timer expires. In theprior art, if the terminal device determines that the timer expires, theterminal device performs BWP switching, in other words, the terminaldevice switches from a current active downlink BWP to a default downlinkBWP in a current secondary serving cell. Optionally, the timer may bereferred to as a BWP fallback timer.

In this step, the terminal device receives the indication message sentby the network device. The indication message indicates the at least onesecondary serving cell, and the indication message is used to instructthe terminal device to deactivate the at least one secondary servingcell. In this case, the terminal device operates on a secondary servingcell in the at least one secondary serving cell, in other words, theterminal device performs data communication on an active downlink BWP ofthe secondary serving cell, and the active downlink BWP is not a defaultdownlink BWP. In this case, it may be determined that a timer associatedwith the secondary serving cell is running.

302 c. The terminal device stops or resets the timer associated with thesecondary serving cell, or the terminal device stops and resets thetimer associated with the secondary serving cell.

In this embodiment, when the conditions in step 301 c are met, theterminal device needs to stop the timer associated with the secondaryserving cell, or the terminal device needs to reset the timer associatedwith the secondary serving cell, or the terminal device needs to stopand reset the timer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step 302 c specifically includes instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop or reset the timerassociated with the secondary serving cell, or instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop and reset the timerassociated with the secondary serving cell.

In this embodiment, if the timer associated with the secondary servingcell is a timer maintained by the physical layer of the terminal device,in step 302 c, the MAC layer of the terminal device sends an instructioncommand to the physical layer of the terminal device, so that thephysical layer of the terminal device stops the timer associated withthe secondary serving cell, or in step 302 c, the MAC layer of theterminal device sends an instruction command to the physical layer ofthe terminal device, so that the physical layer of the terminal deviceresets the timer associated with the secondary serving cell, or in step302 c, the MAC layer of the terminal device sends an instruction commandto the physical layer of the terminal device, so that the physical layerof the terminal device stops and resets the timer associated with thesecondary serving cell.

FIG. 73 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.73, the method is specifically as follows:

S31 c. A network device sends an indication message to a terminaldevice, where the indication message is used to instruct the terminaldevice to deactivate at least one secondary serving cell, a timerassociated with the secondary serving cell is running, and the timer isa timer used by the terminal device to switch from an active downlinkBWP to a default downlink BWP.

In an optional implementation, the indication message is a deactivatecommand. The deactivate command may be a MAC CE for instructing todeactivate at least one secondary serving cell.

S32 c. The terminal device stops or resets the timer associated with thesecondary serving cell, or the terminal device stops and resets thetimer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step S32 c specifically includes instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop or reset the timerassociated with the secondary serving cell, or instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop and reset the timerassociated with the secondary serving cell.

Herein, step 301 c in FIG. 72 is implemented in step S31 c, and step 302c in FIG. 72 is implemented in step S32 c. Details are not describedagain.

In this embodiment, the terminal device receives the indication messagesent by the network device, where the indication message is used toinstruct the terminal device to deactivate the at least one secondaryserving cell, the timer associated with the secondary serving cell isrunning, and the timer is a timer used by the terminal device to switchfrom an active downlink BWP to a default downlink BWP, and the terminaldevice stops or resets the timer associated with the secondary servingcell, or the terminal device stops and resets the timer associated withthe secondary serving cell. Therefore, when the terminal device receivesthe deactivate command sent by the network device, if the timerassociated with the secondary serving cell that needs to be deactivatedis running, it is considered whether the terminal device is to stop orreset the timer associated with the secondary serving cell. In this way,an operating scenario of the timer is provided.

FIG. 74 is a schematic flowchart of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.74, the method is specifically as follows:

401 c. A terminal device determines that a secondary serving celldeactivation timer of a secondary serving cell expires, where the timerassociated with the secondary serving cell is running, and the timer isa timer used by the terminal device to switch from an active downlinkBWP to a default downlink BWP.

In this embodiment, at least one secondary serving cell is configuredfor the terminal device, and each secondary serving cell is associatedwith a timer. The timer is used for timing, and the timer has specifiedduration. When duration for which the timer runs is equal to or exceedsthe specified duration, it is considered that the timer expires. In theprior art, if the terminal device determines that the timer expires, theterminal device performs BWP switching, in other words, the terminaldevice switches from a current active downlink BWP to a default downlinkBWP in a current secondary serving cell. Optionally, the timer may bereferred to as a BWP fallback timer.

In this step, when the terminal device performs data communication on adownlink BWP of a secondary serving cell, if a timer associated with thesecondary serving cell is running, the terminal device needs todetermine whether the secondary serving cell deactivation timer of thesecondary serving cell expires.

402 c. The terminal device stops or resets the timer associated with thesecondary serving cell, or the terminal device stops and resets thetimer associated with the secondary serving cell.

In this embodiment, if the terminal device determines that the secondaryserving cell deactivation timer of the secondary serving cell in step401 c expires, the terminal device needs to stop the timer associatedwith the secondary serving cell, or the terminal device needs to resetthe timer associated with the secondary serving cell, or the terminaldevice needs to stop and reset the timer associated with the secondaryserving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step 302C specifically includes instructing, by the terminaldevice by using a MAC layer of the terminal device, the physical layerof the terminal device to stop or reset the timer associated with thesecondary serving cell, or instructing, by the terminal device by usinga MAC layer of the terminal device, the physical layer of the terminaldevice to stop and reset the timer associated with the secondary servingcell.

In this embodiment, if the timer associated with the secondary servingcell is a timer maintained by the physical layer of the terminal device,in step 402 c, when the terminal device determines that the secondaryserving cell deactivation timer of the secondary serving cell expires,the MAC layer of the terminal device sends an instruction command to thephysical layer of the terminal device, so that the physical layer of theterminal device stops the timer associated with the secondary servingcell, or in step 402 c, the MAC layer of the terminal device sends aninstruction command to the physical layer of the terminal device, sothat the physical layer of the terminal device resets the timerassociated with the secondary serving cell, or in step 402 c, the MAClayer of the terminal device sends an instruction command to thephysical layer of the terminal device, so that the physical layer of theterminal device stops and resets the timer associated with the secondaryserving cell.

FIG. 75 is a signaling diagram of another timer handling methodaccording to an embodiment of the present invention. As shown in FIG.75, the method is specifically as follows:

S41 c. A terminal device determines that a secondary serving celldeactivation timer of a secondary serving cell expires, where the timerassociated with the secondary serving cell is running, and the timer isa timer used by the terminal device to switch from an active downlinkBWP to a default downlink BWP.

S42 c. The terminal device stops or resets the timer associated with thesecondary serving cell, or the terminal device stops and resets thetimer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and step S42 c specifically includes instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop or reset the timerassociated with the secondary serving cell, or instructing, by theterminal device by using a MAC layer of the terminal device, thephysical layer of the terminal device to stop and reset the timerassociated with the secondary serving cell.

Herein, step 401 c in FIG. 74 is implemented in step S41 c, and step402C in FIG. 74 is implemented in step S42. Details are not describedagain.

In this embodiment, the terminal device determines that the secondaryserving cell deactivation timer of the secondary serving cell expires,where the timer associated with the secondary serving cell is running,and the timer is a timer used by the terminal device to switch from anactive downlink BWP to a default downlink BWP, and the terminal devicestops or resets the timer associated with the secondary serving cell, orthe terminal device stops and resets the timer associated with thesecondary serving cell. Therefore, when the terminal device determinesthat the secondary serving cell deactivation timer of the secondaryserving cell expires, it is considered whether the terminal device is tostop or reset the timer associated with the secondary serving cell. Inthis way, an operating scenario of the timer is provided.

FIG. 76 is a schematic structural diagram of a terminal device accordingto an embodiment of this application. As shown in FIG. 76, the terminaldevice includes a receiving module 51, configured to receive a PDCCHorder message sent by a network device, where a timer of the terminaldevice is running, and the timer is a timer used by the terminal deviceto switch from an active downlink BWP to a default downlink BWP, and arunning module 52, configured to start or restart the timer.

The receiving module 51 may perform step 101 c in the method shown inFIG. 68, and the running module 52 may perform step 102 c in the methodshown in FIG. 68.

In an optional implementation, the PDCCH order message includes anidentifier of a downlink BWP, and the downlink BWP indicated by theidentifier of the downlink BWP is not a default downlink BWP.

The terminal device in the embodiment shown in FIG. 76 may be configuredto perform the technical solutions of the embodiments shown in FIG. 68and FIG. 69 in the foregoing methods. Implementation principles andtechnical effects of the terminal device are similar to those in theforegoing embodiments, and details are not described herein again.

FIG. 77 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 77, theterminal device includes a first receiving module 61, configured toreceive an indication message sent by a network device, where theindication message is used to instruct the terminal device to activateat least one secondary serving cell, and a running module 62, configuredto start or restart a timer associated with the secondary serving cell,where the timer is a timer used by the terminal device to switch from anactive downlink BWP to a default downlink BWP.

The first receiving module 61 may perform step 201 c in the method shownin FIG. 70, and the running module 62 may perform step 202 c in themethod shown in FIG. 70.

In a possible design, the secondary serving cell is in an inactivestate.

In an optional implementation, the terminal device further includes asecond receiving module, configured to before the first receiving module61 receives the indication message sent by the network device, receivean RRC message sent by the network device, where the RRC messageincludes indication information, the indication information is used toinstruct to add or modify the at least one secondary serving cell, theRRC message further includes a first downlink BWP of the secondaryserving cell, the first downlink BWP is a downlink BWP that is firstactivated when the secondary serving cell is activated, and the firstdownlink BWP is not a default downlink BWP.

The second receiving module may perform step 203 c in the method shownin FIG. 70.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the running module 62 is specifically configured toinstruct, by using a MAC layer of the terminal device, the physicallayer of the terminal device to start or restart the timer associatedwith the secondary serving cell.

The terminal device in the embodiment shown in FIG. 77 may be configuredto perform the technical solutions of the embodiments shown in FIG. 70and FIG. 71 in the foregoing methods. Implementation principles andtechnical effects of the terminal device are similar to those in theforegoing embodiments, and details are not described herein again.

FIG. 78 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 78, theterminal device includes a receiving module 71, configured to receive anindication message sent by a network device, where the indicationmessage is used to instruct the terminal device to deactivate at leastone secondary serving cell, a timer associated with the secondaryserving cell is running, and the timer is a timer used by the terminaldevice to switch from an active downlink BWP to a default downlink BWP,and a processing module 72, configured to stop or reset the timerassociated with the secondary serving cell, or stop and reset, by theterminal device, the timer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the processing module 72 is specifically configured toinstruct, by using a MAC layer of the terminal device, the physicallayer of the terminal device to stop or reset the timer associated withthe secondary serving cell, or instruct, by using a MAC layer of theterminal device, the physical layer of the terminal device to stop andreset the timer associated with the secondary serving cell.

The receiving module 71 may perform step 301 c in the method shown inFIG. 72, and the processing module 72 may perform step 302C in themethod shown in FIG. 72.

The terminal device in the embodiment shown in FIG. 78 may be configuredto perform the technical solutions of the embodiments shown in FIG. 72and FIG. 73 in the foregoing methods. Implementation principles andtechnical effects of the terminal device are similar to those in theforegoing embodiments, and details are not described herein again.

FIG. 79 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 79, theterminal device includes a determining module 81, configured todetermine that a secondary serving cell deactivation timer of asecondary serving cell expires, where the timer associated with thesecondary serving cell is running, and the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP, and a processing module 82, configured to stop or resetthe timer associated with the secondary serving cell, or stop and reset,by the terminal device, the timer associated with the secondary servingcell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the processing module 82 is specifically configured toinstruct, by using a MAC layer of the terminal device, the physicallayer of the terminal device to stop or reset the timer associated withthe secondary serving cell, or instruct, by using a MAC layer of theterminal device, the physical layer of the terminal device to stop andreset the timer associated with the secondary serving cell.

The determining module 81 may perform step 401 c in the method shown inFIG. 74, and the processing module 82 may perform step 402C in themethod shown in FIG. 74.

The terminal device in the embodiment shown in FIG. 79 may be configuredto perform the technical solutions of the embodiments shown in FIG. 74and FIG. 75 in the foregoing methods. Implementation principles andtechnical effects of the terminal device are similar to those in theforegoing embodiments, and details are not described herein again.

It should be understood that division of the modules in the terminaldevice and the network device is merely logical function division. Inactual implementation, all or some of the modules may be integrated intoone physical entity, or the modules may be physically separated. Inaddition, these modules may all be implemented in a form of softwareinvoked by using a processing element, or may all be implemented in aform of hardware, or some of the modules may be implemented in a form ofsoftware invoked by using a processing element and some of the modulesmay be implemented in a form of hardware. For example, the sendingmodule may be an independently disposed processing element, or may beintegrated into a chip of the terminal device or the network device forimplementation. In addition, the sending module may be stored in amemory in the terminal device or the network device in a form of aprogram, and be invoked by a processing element in the terminal deviceor the network device, to perform the functions of the module.Implementations of other modules are similar to the implementation ofthe sending module. In addition, all or some of the modules may beintegrated together, or may be implemented separately. The processingelement herein may be an integrated circuit with a signal processingcapability. In an implementation process, the steps of the foregoingmethods or the foregoing modules may be implemented by using anintegrated logic circuit of hardware in the processor element or byusing a software instruction. In addition, the receiving module is areceiving control module, and may receive, by using a receivingapparatus, for example, an antenna or a radio frequency apparatus, ofthe terminal device or the network device, information sent by thenetwork device. The sending module is a sending control module, and maysend information to the terminal device by using a sending apparatus,for example, an antenna or a radio frequency apparatus, of the networkdevice or the terminal device.

For example, the foregoing modules may be configured as one or moreintegrated circuits for implementing the foregoing methods, for example,one or more application-specific integrated circuits (ASIC), one or moremicroprocessors (DSP), or one or more field programmable gate arrays(FPGA). For another example, when one of the foregoing modules isimplemented in a form of a program scheduled by using a processingelement, the processing element may be a general-purpose processor, forexample, a central processing unit (CPU) or another processor that caninvoke the program. For another example, these units may be integratedtogether and implemented in a form of a system-on-a-chip (SOC).

FIG. 80 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 80, theterminal device may be configured to perform the actions or steps of theterminal device in the embodiments shown in FIG. 68 and FIG. 69. Theterminal device includes a receiver 411, a transmitter 412, a processor1413, and a memory 144.

The receiver 1411 is configured to receive a PDCCH order message sent bya network device, where a timer of the terminal device is running, andthe timer is a timer used by the terminal device to switch from anactive downlink BWP to a default downlink BWP.

The processor 1413 is configured to start or restart the timer.

In an optional implementation, the PDCCH order message includes anidentifier of a downlink BWP, and the downlink BWP indicated by theidentifier of the downlink BWP is not a default downlink BWP.

The receiver 1411 may implement the function of the receiving module 51in the terminal device shown in FIG. 76, and the processor 1413 mayimplement the function of the running module 52 in the terminal deviceshown in FIG. 76. Further, the receiver 1411 may perform step 101 c inthe method shown in FIG. 68, and the processor 1413 may perform step 102c in the method shown in FIG. 68, or the receiver 1411 may perform stepS11 c in the method shown in FIG. 69, and the processor 1413 may performstep S12 c in the method shown in FIG. 69.

The terminal device in the embodiment shown in FIG. 80 may be configuredto perform the technical solutions of the foregoing method embodiments.Implementation principles and technical effects of the terminal deviceare similar to those in the foregoing embodiments, and details are notdescribed herein again.

The receiver 1411 and the transmitter 1412 may be connected to anantenna. In a downlink direction, the receiver 1411 receives, by usingthe antenna, information sent by the network device, and the transmitter1412 sends, by using the antenna, the information to the processor 1413for processing. In an uplink direction, the processor 1413 processesdata of the terminal device, and sends data obtained after theprocessing to the network device by using the transmitter 1412.

The memory 1414 is configured to store programs for implementing theforegoing method embodiments or the modules in the embodiment shown inFIG. 76, and the processor 1413 invokes the programs to perform theoperations in the foregoing method embodiments, to implement the modulesshown in FIG. 76.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more application-specific integrated circuits (ASIC),one or more microprocessors (DSP), or one or more field programmablegate arrays (FPGA).

FIG. 81 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 81, theterminal device may be configured to perform the actions or steps of theterminal device in the embodiments shown in FIG. 70 and FIG. 71. Theterminal device includes a receiver 1511, a transmitter 1512, aprocessor 1513, and a memory 1514.

The receiver 1511 is configured to receive an indication message sent bya network device, where the indication message is used to instruct theterminal device to activate at least one secondary serving cell.

The processor 1513 is configured to start or restart a timer associatedwith the secondary serving cell, where the timer is a timer used by theterminal device to switch from an active downlink BWP to a defaultdownlink BWP.

In a possible design, the secondary serving cell is in an inactivestate.

In an optional implementation, the receiver 1511 is further configuredto before receiving the indication message sent by the network device,receive an RRC message sent by the network device, where the RRC messageincludes indication information, the indication information is used toinstruct to add or modify the at least one secondary serving cell, theRRC message further includes a first downlink BWP of the secondaryserving cell, the first downlink BWP is a downlink BWP that is firstactivated when the secondary serving cell is activated, and the firstdownlink BWP is not a default downlink BWP.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the processor 1513 is specifically configured to instruct,by using a MAC layer of the terminal device, the physical layer of theterminal device to start or restart the timer associated with thesecondary serving cell.

The receiver 1511 may implement the functions of the first receivingmodule 61 and the second receiving module in the terminal device shownin FIG. 77, and the processor 1513 may implement the function of therunning module 62 in the terminal device shown in FIG. 77. Further, thereceiver 1511 may perform step 201 c and step 203 c in the method shownin FIG. 70, and the processor 1513 may perform step 202 c in the methodshown in FIG. 70, or the receiver 1511 may perform step S21 c and stepS22 c in the method shown in FIG. 71, and the processor 1513 may performstep S23 c in the method shown in FIG. 71.

The terminal device in the embodiment shown in FIG. 81 may be configuredto perform the technical solutions of the foregoing method embodiments.Implementation principles and technical effects of the terminal deviceare similar to those in the foregoing embodiments, and details are notdescribed herein again.

The receiver 1511 and the transmitter 1512 may be connected to anantenna. In a downlink direction, the receiver 1511 receives, by usingthe antenna, information sent by the network device, and the transmitter1512 sends, by using the antenna, the information to the processor 1513for processing. In an uplink direction, the processor 1513 processesdata of the terminal device, and sends data obtained after theprocessing to the network device by using the transmitter 1512.

The memory 1514 is configured to store programs for implementing theforegoing method embodiments or the modules in the embodiment shown inFIG. 77, and the processor 1513 invokes the programs to perform theoperations in the foregoing method embodiments, to implement the modulesshown in FIG. 77.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

FIG. 82 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 82, theterminal device may be configured to perform the actions or steps of theterminal device in the embodiments shown in FIG. 72 and FIG. 73. Theterminal device includes a receiver 1611, a transmitter 1612, aprocessor 1613, and a memory 1614.

The receiver 1611 is configured to receive an indication message sent bya network device, where the indication message is used to instruct theterminal device to deactivate at least one secondary serving cell, atimer associated with the secondary serving cell is running, and thetimer is a timer used by the terminal device to switch from an activedownlink BWP to a default downlink BWP.

The processor 1613 is configured to stop or reset the timer associatedwith the secondary serving cell, or stop and reset, by the terminaldevice, the timer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the processor 1613 is specifically configured to instruct,by using a MAC layer of the terminal device, the physical layer of theterminal device to stop or reset the timer associated with the secondaryserving cell, or instruct, by using a MAC layer of the terminal device,the physical layer of the terminal device to stop and reset the timerassociated with the secondary serving cell.

The receiver 1611 may implement the function of the receiving module 71in the terminal device shown in FIG. 78, and the processor 1613 mayimplement the function of the processing module 72 in the terminaldevice shown in FIG. 78. Further, the receiver 1611 may perform step301C in the method shown in FIG. 72, and the processor 1613 may performstep 302C in the method shown in FIG. 72, or the receiver 1611 mayperform step S31 c in the method shown in FIG. 73, and the processor1613 may perform step S32 c in the method shown in FIG. 73.

The terminal device in the embodiment shown in FIG. 82 may be configuredto perform the technical solutions of the foregoing method embodiments.Implementation principles and technical effects of the terminal deviceare similar to those in the foregoing embodiments, and details are notdescribed herein again.

The receiver 1611 and the transmitter 1612 may be connected to anantenna. In a downlink direction, the receiver 1611 receives, by usingthe antenna, information sent by the network device, and the transmitter1612 sends, by using the antenna, the information to the processor 1613for processing. In an uplink direction, the processor 1613 processesdata of the terminal device, and sends data obtained after theprocessing to the network device by using the transmitter 1612.

The memory 1614 is configured to store programs for implementing theforegoing method embodiments or the modules in the embodiment shown inFIG. 78, and the processor 1613 invokes the programs to perform theoperations in the foregoing method embodiments, to implement the modulesshown in FIG. 78.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

FIG. 83 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 83, theterminal device may be configured to perform the actions or steps of theterminal device in the embodiments shown in FIG. 74 and FIG. 75. Theterminal device includes a receiver 1711, a transmitter 1712, aprocessor 1713, and a memory 1714.

The processor 1713 is configured to determine that a secondary servingcell deactivation timer of a secondary serving cell expires, where thetimer associated with the secondary serving cell is running, and thetimer is a timer used by the terminal device to switch from an activedownlink BWP to a default downlink BWP, and stop or reset the timerassociated with the secondary serving cell, or stop and reset, by theterminal device, the timer associated with the secondary serving cell.

In an optional implementation, the timer associated with the secondaryserving cell is a timer maintained by a physical layer of the terminaldevice, and the processor 1713 is specifically configured to instruct,by using a MAC layer of the terminal device, the physical layer of theterminal device to stop or reset the timer associated with the secondaryserving cell, or instruct, by using a MAC layer of the terminal device,the physical layer of the terminal device to stop and reset the timerassociated with the secondary serving cell.

The processor 1713 may implement the functions of the determining module81 and the processing module 82 in the terminal device shown in FIG. 79.Further, the processor 1713 may perform step 401 c and step 402C in themethod shown in FIG. 74, or the processor 1713 may perform steps S41 cand S42 c in the method shown in FIG. 75.

The terminal device in the embodiment shown in FIG. 83 may be configuredto perform the technical solutions of the foregoing method embodiments.Implementation principles and technical effects of the terminal deviceare similar to those in the foregoing embodiments, and details are notdescribed herein again.

The receiver 1711 and the transmitter 1712 may be connected to anantenna. In a downlink direction, the receiver 1711 receives, by usingthe antenna, information sent by the network device, and the transmitter1712 sends, by using the antenna, the information to the processor 1713for processing. In an uplink direction, the processor 1713 processesdata of the terminal device, and sends data obtained after theprocessing to the network device by using the transmitter 1712.

The memory 1714 is configured to store programs for implementing theforegoing method embodiments or the modules in the embodiment shown inFIG. 79, and the processor 1713 invokes the programs to perform theoperations in the foregoing method embodiments, to implement the modulesshown in FIG. 79.

Alternatively, some or all of the foregoing modules may be implementedin a form of an integrated circuit that is embedded in a chip of theuser equipment. The modules may be implemented separately or may beintegrated together. The foregoing modules may be configured as one ormore integrated circuits for implementing the foregoing methods, forexample, one or more ASICs, one or more DSPs, or one or more FPGAs.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, all or some of the embodiments maybe implemented in a form of a computer program product. The computerprogram product includes one or more computer instructions. When thecomputer program instructions are loaded and executed on a computer, allor some of the procedures or functions according to the embodiments ofthis application are generated. The computer may be a general-purposecomputer, a dedicated computer, a computer network, or anotherprogrammable apparatus. The computer instructions may be stored in acomputer readable storage medium or may be transmitted from a computerreadable storage medium to another computer readable storage medium. Forexample, the computer instructions may be transmitted from a website,computer, server, or data center to another website, computer, server,or data center in a wired (for example, a coaxial cable, an opticalfiber, or a digital subscriber line (digital subscriber line, DSL)) orwireless (for example, infrared, radio, or microwave) manner. Thecomputer readable storage medium may be any usable medium accessible toa computer, or a data storage device, such as a server or a data center,integrating one or more usable media. The usable medium may be amagnetic medium (for example, a floppy disk, a hard disk, or a magnetictape), an optical medium (for example, a DVD), a semiconductor medium(for example, a solid state disk (SSD)), or the like.

A person skilled in the art should be aware that in the foregoing one ormore examples, functions described in the embodiments of thisapplication may be implemented by hardware, software, firmware, or anycombination thereof. When this application is implemented by software,these functions may be stored in a computer readable medium ortransmitted as one or more instructions or code in the computer readablemedium. The computer readable medium includes a computer storage mediumand a communications medium, where the communications medium includesany medium that enables a computer program to be transmitted from oneplace to another. The storage medium may be any usable medium accessibleto a general-purpose or dedicated computer.

1-32. (canceled)
 33. A random access method, comprising: receiving, byuser equipment, a radio resource control (RRC) connectionreconfiguration message from a first network device, wherein the RRCconnection reconfiguration message is included in a first message sentby a second network device to the first network device, and wherein theRRC connection reconfiguration message indicates a primary serving cellof the second network device for the user equipment, and furtherindicates an active bandwidth part (BWP) in the primary serving cell;and initiating, by the user equipment, a random access procedure on theactive BWP.
 34. The method according to claim 33, wherein the firstnetwork device is a source network device, and the second network deviceis a target network device, the first message is a handover requestacknowledgment message.
 35. The method according to claim 34, whereinthe RRC connection reconfiguration message includes a first BWPidentifier indicating the active BWP.
 36. The method according to claim35, wherein the active BWP includes an uplink BWP and a downlink BWP.37. The method according to claim 33, wherein the first network deviceis a primary network device node, wherein the second network device is asecondary network device node, and wherein the first message is asecondary node addition request acknowledgment message.
 38. The methodaccording to claim 37, wherein the RRC connection reconfigurationmessage includes a first BWP identifier indicating the active BWP. 39.The method according to claim 37, wherein the active BWP includes anuplink BWP and a downlink BWP.
 40. The method according to claim 33,wherein the RRC connection reconfiguration message includes a first BWPidentifier indicating the active BWP.
 41. The method according to claim33, wherein the active BWP includes an uplink BWP and a downlink BWP.42. A user equipment, comprising: a receiver, a processor; and anon-transitory computer-readable storage medium storing a program to beexecuted by the processor, the program including instructions to:receive, through the receiver, a radio resource control (RRC) connectionreconfiguration message from a first network device, wherein the RRCconnection reconfiguration message is included in a first message sentby a second network device to the first network device, and wherein theRRC connection reconfiguration message indicates a primary serving cellof the second network device for the user equipment, and furtherindicates an active bandwidth part (BWP) in the primary serving cell;and initiate a random access procedure on the active BWP.
 43. The userequipment according to claim 42, wherein the first network device is asource network device, wherein the second network device is a targetnetwork device, and wherein the first message is a handover requestacknowledgment message.
 44. The user equipment according to claim 42,wherein the first network device is a primary network device node,wherein the second network device is a secondary network device node,and wherein the first message is a secondary node addition requestacknowledgment message.
 45. The user equipment according to claim 42,wherein the RRC connection reconfiguration message includes a first BWPidentifier indicating the active BWP.
 46. The user equipment accordingto claim 42, wherein the active BWP includes an uplink BWP and adownlink BWP.
 47. A non-transitory computer-readable storage mediumhaving stored thereon instructions which, when executed by a computer,cause the computer to perform a random access method, comprising:receiving, by a user equipment, a radio resource control (RRC)connection reconfiguration message from a first network device; whereinthe RRC connection reconfiguration message is included in a firstmessage, wherein the first message is sent by a second network device tothe first network device, and wherein the RRC connection reconfigurationmessage indicates a primary serving cell of the second network devicefor the user equipment, and further indicates an active bandwidth part(BWP) in the primary serving cell; and initiating, by the userequipment, a random access procedure on the active BWP.
 48. Thecomputer-readable storage medium according to claim 47, wherein thefirst network device is a source network device, wherein the secondnetwork device is a target network device, and wherein the first messageis a handover request acknowledgment message.
 49. The computer-readablestorage medium according to claim 47, wherein the first network deviceis a primary network device node, wherein the second network device is asecondary network device node, and wherein the first message is asecondary node addition request acknowledgment message.
 50. Thecomputer-readable storage medium according to claim 47, wherein the RRCconnection reconfiguration message includes a first BWP identifierindicating the active BWP.
 51. The computer-readable storage mediumaccording to claim 47, wherein the active BWP includes an uplink BWP anda downlink BWP.